WO2014191138A1 - Large capacitance electronic components - Google Patents

Large capacitance electronic components Download PDF

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Publication number
WO2014191138A1
WO2014191138A1 PCT/EP2014/058160 EP2014058160W WO2014191138A1 WO 2014191138 A1 WO2014191138 A1 WO 2014191138A1 EP 2014058160 W EP2014058160 W EP 2014058160W WO 2014191138 A1 WO2014191138 A1 WO 2014191138A1
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Prior art keywords
nanoparticles
electrodes
electrolyte
active material
photodetector
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PCT/EP2014/058160
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French (fr)
Inventor
Emmanuel LHUILLIER
Benoît DUBERTRET
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Solarwell
Fonds De L'espci - Georges Charpak
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Publication of WO2014191138A1 publication Critical patent/WO2014191138A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof  ; Multistep manufacturing processes therefor
    • H01L29/40—Electrodes ; Multistep manufacturing processes therefor
    • H01L29/43—Electrodes ; Multistep manufacturing processes therefor characterised by the materials of which they are formed
    • H01L29/49—Metal-insulator-semiconductor electrodes, e.g. gates of MOSFET
    • H01L29/4908—Metal-insulator-semiconductor electrodes, e.g. gates of MOSFET for thin film semiconductor, e.g. gate of TFT
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-SENSITIVE DEVICES, OF THE ELECTROLYTIC TYPE
    • H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
    • H01G9/20—Light-sensitive devices
    • H01G9/2054—Light-sensitive devices comprising a semiconductor electrode comprising AII-BVI compounds, e.g. CdTe, CdSe, ZnTe, ZnSe, with or without impurities, e.g. doping materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
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    • H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof  ; Multistep manufacturing processes therefor
    • H01L29/02—Semiconductor bodies ; Multistep manufacturing processes therefor
    • H01L29/06—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions
    • H01L29/0657—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by the shape of the body
    • H01L29/0665—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by the shape of the body the shape of the body defining a nanostructure
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof  ; Multistep manufacturing processes therefor
    • H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
    • H01L29/68—Types of semiconductor device ; Multistep manufacturing processes therefor controllable by only the electric current supplied, or only the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched
    • H01L29/76—Unipolar devices, e.g. field effect transistors
    • H01L29/772—Field effect transistors
    • H01L29/78—Field effect transistors with field effect produced by an insulated gate
    • H01L29/786—Thin film transistors, i.e. transistors with a channel being at least partly a thin film
    • H01L29/78681—Thin film transistors, i.e. transistors with a channel being at least partly a thin film having a semiconductor body comprising AIIIBV or AIIBVI or AIVBVI semiconductor materials, or Se or Te
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof  ; Multistep manufacturing processes therefor
    • H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
    • H01L29/68—Types of semiconductor device ; Multistep manufacturing processes therefor controllable by only the electric current supplied, or only the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched
    • H01L29/76—Unipolar devices, e.g. field effect transistors
    • H01L29/772—Field effect transistors
    • H01L29/78—Field effect transistors with field effect produced by an insulated gate
    • H01L29/786—Thin film transistors, i.e. transistors with a channel being at least partly a thin film
    • H01L29/78696—Thin film transistors, i.e. transistors with a channel being at least partly a thin film characterised by the structure of the channel, e.g. multichannel, transverse or longitudinal shape, length or width, doping structure, or the overlap or alignment between the channel and the gate, the source or the drain, or the contacting structure of the channel
    • H—ELECTRICITY
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    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/02—Details
    • H01L31/0224—Electrodes
    • H01L31/022408—Electrodes for devices characterised by at least one potential jump barrier or surface barrier
    • H—ELECTRICITY
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    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/0248—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies
    • H01L31/0352—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by their shape or by the shapes, relative sizes or disposition of the semiconductor regions
    • H01L31/035209—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by their shape or by the shapes, relative sizes or disposition of the semiconductor regions comprising a quantum structures
    • H01L31/035218—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by their shape or by the shapes, relative sizes or disposition of the semiconductor regions comprising a quantum structures the quantum structure being quantum dots
    • H—ELECTRICITY
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    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/08—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors
    • H01L31/10—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors characterised by at least one potential-jump barrier or surface barrier, e.g. phototransistors
    • H01L31/101—Devices sensitive to infrared, visible or ultraviolet radiation
    • H01L31/112—Devices sensitive to infrared, visible or ultraviolet radiation characterised by field-effect operation, e.g. junction field-effect phototransistor
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K30/00—Organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation
    • H10K30/60—Organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation in which radiation controls flow of current through the devices, e.g. photoresistors
    • H10K30/65—Light-sensitive field-effect devices, e.g. phototransistors
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/542—Dye sensitized solar cells
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/549—Organic PV cells
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present invention relates generally to electronic components. More particularly, this invention relates to transistors, photodetectors and photo transistors. This invention also relates to the manufacturing process and the use of said electronic components.
  • a transistor is a semiconductor device used to amplify and switch electronic signals and electrical power.
  • the transistor is the fundamental building block of modern electronic devices, and is ubiquitous in modern electronic systems.
  • the field effect transistor has been introduced as a system to tune the conductance of a material, that we will name “the active material”, through the modulation of its charge-carrier density.
  • the active material is in general a semiconductor. It can be a single crystal obtained by top-down methods, thin film techniques, molecular beam epitaxy, or molecular organic chemical vapor deposition. It can also be obtained using the assembly of crystalline nanoparticles.
  • a FET is a three electrodes device where a first electrode, the gate electrode, is used to control the carrier density of the channel connecting the two other electrodes: the drain and the source electrodes.
  • the good performances of a FET rely in the optimization of two parameters: the conductivity of the active material, and the charge density that can be achieved in the active material.
  • the conductivity of the active material In the case of FET with an active material obtained from an assembly of nanoparticles, which offers extremely easy and cheap process compatible with flexible electronics, the main efforts have been geared toward the enhancement of the active material conductivity, with recent great success.
  • the charge density of the active material has remained comparatively poor, and its modulation is classically limited to the interface of the active material and the dielectric.
  • a typical strategy is to use a Si/Si0 2 substrate, where the silica layer is used as a dielectric layer.
  • Application of a bias over the oxide capacitively induces charges at the surface of the oxide. If nanoparticles are deposited on the surface it is possible to induce a change of the carrier concentration. Indeed the surface capacitance is given by wherein £Q is the vacuum permittivity, ⁇ ⁇ is the relative
  • dielectric constant of the dielectric layer and t is the thickness of dielectric.
  • Electrolytic field effect transistors are typically composed successively of a substrate, two electrodes, a layer of active material, a liquid or solid electrolyte and a third electrode. A voltage or current applied to one pair of the transistor's electrodes, the control electrodes, changes the current flowing through another pair of terminals, the controlled current. Since solid state FETs remain limited to the low charging domain, many efforts have been devoted to try to improve the charging through the combined use of liquid electrolyte and colloidal nanoparticles, as described for instance in electro chromic nanocrystal quantum dots, Science 291, 2390 (2001) or electrochemical gating: a method to tune and monitor the (opto)electronic properties of functional materials, Electrochimica Acta 53, 1140 (2007).
  • FET with nanoparticles as an active material can be found, such as the one proposed in the United States patent application US 2010/0308299.
  • the charge densities modulation of the active materials is limited to the interface between the dielectric and the active materials, without charging in the whole volume of the active material.
  • US 2010/0308299 an electronic component comprising two electrodes, a layer of nanoparticles and a dielectric layer having at least one common interface with at least a part of the nanoparticles is described.
  • the layer of nanoparticles includes an electronically conducting compound of a metal and an element of group VI of the periodic table.
  • the device comprises a highly conducting channel at zero applied voltage at the gate, which generates useless energy consumption in the off state which is not the case in the current invention.
  • the tuning of the conductance under a gate bias remains limited to a factor of 350 in US 2010/0308299.
  • ions from the electrolyte can migrate within the bulk of the active material, although the polymer matrix supporting the electrolytes does not penetrate into the active material.
  • This ion migration comes with a bulk charge of the active material and gives charge densities that are increased by several orders of magnitude.
  • the present invention aims at describing a new family of transistors having improved characteristics and high gain i.e. with a large-current variation of the controlled current resulting from a small variation of the voltage applied to the control electrodes.
  • the general approach to describe the active material charging process through an electrolyte relies either on the formation of a double ionic layer at the interface between the electrolyte and the active material, or through redox processes at the surface of the active material. For example in an n-type material, cations from the electrolyte will densely accumulate at the surface (but still in the electrolyte) and will face a negatively charged layer of semiconductor. Moreover in the electrolyte a layer of anions comes on the top of the cations layer to screen them and lead to a null electric field in the bulk of the electrolyte. The charging of the semiconductor occurs through the injection by the source electrodes of electrons. As explained hereabove, so far this process leads to a
  • the key advantage to use electrolyte is their ability to charge a nanomaterial into the full volume of the film by letting the ions percolate into the void of the film.
  • An - of charge is given by the expression ph where e the proton charge, N the total number of nanoplatelets absorbing, ⁇ the cross section of the particle, ⁇ the minority carrier lifetime into the film, ⁇ the power flux per unit area and ⁇ ph the energy of the incident photon.
  • equation (1) corresponds to the photocurrent in the photoconductive mode, but the enhanced photoresponse is related to the term 10 s
  • the responsivity of a light detector is defined as the ratio of the photogenerated current over the photon flux. It describes the ability of a material to convert light in an electrical signal. The more electrons generated per absorbed photon, the higher the performance. To enhance the number of photogenerated electron people have used optical process such as multiexciton generation or electrical process such as avalanche process. In the current invention we want to use the electrolyte transistor as possible strategy to tune the nanoparticle film responsivity.
  • the change in the responsivity (R) compared to the regular photodetector (Rdet) is given by
  • Photoresponse enhancement (2) One of the aims of this invention is to take advantage of the photoresponse enhancement brought by the gating and in particular the strong non linearity of the current with the carrier density.
  • the current invention will be operated at a bias close to the turn on voltage of the device, where the device remains poorly conductive in the dark. The excess of charge photogenerated will consequently lead to a rise of the current which is more important than the one obtained in absence of gating.
  • the photoconduction properties of colloidal nanoparticles is combined with the electrolyte gating to enhance the optoelectronic properties of the electronic component.
  • the present invention is applicable to transistors and to photodetection devices, such as for example photo transistors.
  • Photodetector or phototransistor generates a photocurrent under light illumination.
  • the present invention allows developing photodetector operating as a phototransistor, which takes full advantage of the current non-linearity with the nanoparticle charging.
  • Phototransistor based on colloidal nanoparticles remains mostly undeveloped since usual transistor based on back-gating through a solid dielectric can only charge a thin layer of quantum dot (tens of nanometer), while photodetection generally request thicker film (several hundred nanometer) in order to absorb a significant part of the incident light.
  • bulk doping of the active material can be achieved in the current invention is a key advantage.
  • Another strong improvement of our technology compared to existing devices is the fact that ion gel polymer allows a drastic size reduction of the device compared to liquid electrolyte gating.
  • the invention is also based on the implementation of the right pair of nanoparticles surface chemistry/electrolyte. It is therefore another object of the present invention to elaborate an electronic component which takes full advantage of the optimized surface chemistry of the active material and which coupled the surface chemistry with a chosen electrolyte. Said electronic component of the invention can thus provide a high current modulation thanks to the volume charging of the active material.
  • This invention relates to a photodetector comprising a substrate, at least three electrodes, an active material comprising a plurality of inorganic semiconductor nanoparticles bridging at least two electrodes and an electrolyte.
  • the substrate and/or the electrolyte are transparent in at least a wavelength window compatible with the absorption spectrum of the plurality of nanoparticles.
  • said nanoparticles are nanocrystals, nanosheets, nanorods, nanoplatelets, nanoparticles, nanowires, nanopowders, nanotubes, nanotetrapods, nanoribbons, nanocubes, quantum dots and/or combinations thereof.
  • said electrolyte is liquid, polymer, ion-gel or solid.
  • said photodetector is a phototransistor.
  • the at least two electrodes bridged by a plurality of inorganic semiconductor nanoparticles are spaced by a nanogap whose size ranges from 1 nanometer to 1 micrometer.
  • said photodetector comprises at least two pluralities of various nanoparticles which can be independently addressed using the gate voltage as a switch.
  • a bicolor or multicolor photodetector or phototransistor is achieved and the gate bias may tune the photocurrent spectrum.
  • bulk charging is achieved within said active material comprising a plurality of nanoparticles.
  • said active material comprising a plurality of nanoparticles has a thickness from 10 nanometers to 1 centimeter, preferably from 10 nanometers to 10 micrometers, more preferably from 10 nanometers to 1 micrometer.
  • This invention also relates to a method for producing a photodetector, the method comprising: a) the deposition of the first and the second electrodes onto a substrate, b) the preparation of a solution of nanoparticles,
  • step b') the deposition of the previous solution onto the electrodes and substrate, c') if step b') is not implemented, nanoparticle's ligand exchange step on the active material comprising a plurality of nanoparticles,
  • the deposition of nanoparticles is achieved by drop casting or spin coating, dip coating, spray casting, screen printing, inkjet printing, sputtering techniques, evaporation techniques electrophoretic deposition, or vacuum methods.
  • This invention also relates to a photodetector operating as in photovoltaic mode or a LED, comprising the photodetector as disclosed herein, wherein a pn junction is formed between two of the electrodes.
  • This invention also relates to an array comprising a plurality of photodetectors according to the present invention.
  • a readout circuit is connected to the plurality of photodetectors.
  • the plurality of photodetectors comprises a first plurality of photodetectors and a second plurality of photodetectors and wherein the band gap of the first plurality of photodetectors is different from the band gap of the second plurality.
  • This invention also relates to a focal plane array for use in an imaging device comprising an array of photodetectors according to the present invention.
  • Active material refers to the compound (usually a semiconductor) that bridges the source electrode and the drain electrode.
  • the conductivity of the active material can be modulated with a gate electrode.
  • the conductivity of the active material is tuned with the gate voltage so that the conductivity of the active material increases non-linearly with the absorption of photons.
  • Charged in volume refers to a process by which the capacity of the plurality of nanoparticles forming the active material increases linearly with the film thickness, even if the electrolyte matrix is limited at the interface of the top of the nanoparticles' film, and does not permeate into the film.
  • Double layer refers to a structure which describes the variation of electric potential near an interface. If a material is in contact with an electrolyte, a single layer of negative or positive ions from the electrolyte will form in close proximity to the material and a second layer with a preponderance of respectively positive or negative ions will form proximate the aforementioned respectively negative or positive ions forming the so-called double layer.
  • a film refers to a single or multiple layers or coating of thin-or thick-material.
  • a film is a porous or not, ordered or not, assembly of nanoparticles, which may be flat or rough.
  • Nanoparticle refers to a particle of any shape having at least one dimension in the 0.1 to 100 nanometers range.
  • This invention relates to an electronic component which comprises a substrate, at least a first and a second electrodes, an active material comprising a plurality of nanoparticles and an electrolyte.
  • the present invention provides an electronic component which comprises a substrate, at least three electrodes, an active material comprising a plurality of nanoparticles and an electrolyte.
  • the electronic component of the invention is a photodetector.
  • the present invention provides a photodetector which comprises a substrate, at least three electrodes, an active material comprising a plurality of nanoparticles and an electrolyte.
  • the active material comprising a plurality of nanoparticles is implemented into a film of nanoparticles.
  • the substrate or body may be formed from silicon, silicon dioxide, aluminum oxide, sapphire, germanium, gallium arsenide, an alloy of silicon and germanium, indium phosphide, indium tin oxide, fluorine doped tin oxide, graphene, glass and its derivative, plastic material or any material that a person skilled in the art would find suitable.
  • the substrate is made of a plastic substrate coated with a conducting material, such as indium tin oxide coating on polyethylene terephthalate.
  • the substrate may be form from ZnS, ZnSe InP, CdZnTe, ZnTe, GaSb, or mixture thereof.
  • the substrate may comprise an oxide layer acting as an electronic insulator.
  • the substrate may comprise several layers with an oxide layer on the top, such as for example a Si0 2 layer on a Si layer.
  • the thickness of the oxide layer is from 10 nanometers to 100 micrometers, preferably from 30 nanometers to 1 micrometer, more preferably from 100 nanometers to 1 micrometer.
  • the substrate may be rigid or non-rigid. According to a preferred embodiment, the substrate is rigid. According to another embodiment, the substrate is flexible and/or stretchable.
  • the substrate is transparent.
  • the substrate is transparent in a wavelength window compatible with the absorption spectrum of the plurality of nanoparticles.
  • Compatible means herein that the substrate is at least partly transparent in the range of wavelength wherein the plurality of nanoparticles is absorbing.
  • Partly transparent means herein that the substrate has a transmittance of at least 50%, preferably at least 75%, more preferably at least 90%.
  • the substrate is transparent in the visible, i.e. in a wavelength range from about 380 nanometers to about 750 nanometers. In one embodiment, the substrate is transparent in the ultraviolet range of wavelength, i.e. in a wavelength range from about 10 nanometers to about 380 nanometers.
  • the substrate is transparent in the infrared range of wavelength, i.e. in the wavelength range from about 750 nanometers to about 1 000 000 nanometers, preferably from about 750 nanometers to about 50 000 nanometers, more preferably from about 750 nanometers to about 3000 nanometers.
  • the substrate is partly transparent in the visible and/or in the ultraviolet range of wavelength and/or in the infrared range of wavelength.
  • the substrate transparency window is at least lnm large, preferably at least lOnm large and more preferably above 50nm large. In one embodiment, the substrate is transparent in two wavelength windows compatible with the absorption spectrum of the plurality of nanoparticles.
  • the substrate transparency window is made of several windows in order to fit the absorption spectrum of the multicolor detector, preferably of several narrow transparency windows i.e. of at most 50 nm large.
  • the electronic component, preferably the photodetector, of the present invention comprises another substrate opposite to the first substrate.
  • the electronic component of the present invention comprises 2 electrodes.
  • the electronic component of the present invention comprises 3 electrodes.
  • the electronic component of the present invention comprises 4 electrodes.
  • the electronic component, preferably the photodetector, of the present invention comprises enough electrodes to build a focal plane array where the active component is the current invention.
  • a first and a second electrodes act as source and drain for the electronic component, preferably the photodetector.
  • a first and a second electrode preferably the source and drain electrodes, are interdigitated.
  • the source and the drain electrodes are located on the substrate.
  • the source and the drain electrodes are located on the active material comprising a plurality of nanoparticles.
  • the active material is located between the source and the drain electrodes thereby bridging said two electrodes.
  • the electronic component preferably the photodetector, comprises a source electrode; a drain electrode disposed so as to be separated from the source electrode, forming a gap between the source and drain electrodes; an active material bridging the gap between the source and drain electrodes and thus forming a transistor channel; and a gate electrode positioned so as to be separated from the source electrode, the drain electrode and the semiconductor layer; wherein an electrolyte is disposed so as to contact at least a part of both the gate electrode and the active material.
  • the electronic component preferably the photodetector, comprises a third electrode, which acts as the gate.
  • the gate electrode is located on the electrolyte. In one embodiment, the gate electrode is located on the substrate.
  • the electronic component preferably the photodetector, comprises a fourth electrode, which acts as the substrate electrode.
  • the fourth electrode is located on the back of the substrate.
  • At least one of the electrodes has a thickness from 1 to 1000 nanometers, preferably from 10 to 100 nanometers, more preferably from 20 to 75 nanometers.
  • At least one of the electrodes comprises an electrochemically inert material such as for example gold, platinum, palladium, silver.
  • At least one of the electrodes comprises any suitable conductive material such as for example gold, silver, copper, chromium, lithium fluoride, titanium, aluminum, silicon, magnesium, indium and conductive alloys.
  • at least one electrode is formed form transparent conducting layer made for example from transparent conducting oxides such as indium tin oxide, fluorine doped tin oxide, zinc oxide, doped zinc oxide.
  • At least one of the electrodes is a doped semiconductor.
  • At least one of the electrodes comprises nanoparticles of the same nature as the nanoparticles of the active material comprising a plurality of nanoparticles.
  • At least one of the electrodes is a carbon based electrode, a graphite electrode, a graphene electrode, an electrode comprising carbon nanotube, or a metal electrode coated with carbon.
  • At least one of the electrodes is a metal foil or any material that has been metalized previously.
  • conductive layer has the same meaning as electrode.
  • At least two electrodes are spaced by a nanogap.
  • two of the three electrodes, preferably the source and drain electrodes, are spaced by a nanogap.
  • the size of said nanogap (i.e. the inter-electrodes distance) ranges from 0.1 nanometer to 1 000 nanometers, preferably from 0.1 nanometer to 200 nanometers, more preferably from 3 nanometers to 100 nanometers.
  • the depth of said nanogap ranges from 0.1 nm to 10 ⁇ , preferably from 0.1 nm to 1 ⁇ , more preferably from 1 nm to 100 nm.
  • the length of said nanogap ranges from 1 nanometer to 10 millimeters, preferably from 5 nanometers to 1 millimeter, more preferably from 10 nanometers to 100 micrometers.
  • at least one of the nanogap electrodes is not tapered or pointed.
  • the active material comprises a plurality of nanoparticles, preferably a plurality of nano sheets.
  • the active material comprises at least two pluralities of various nanoparticles. In one embodiment, the active material comprising a plurality of nanoparticles comprises semiconductor particles.
  • the nanoparticles of the invention are inorganic.
  • the nanoparticles of the invention are colloidal.
  • the nanoparticles of the invention are crystalline.
  • the active material comprising a plurality of nanoparticles comprises oriented nanoparticles.
  • the at least one active material does not comprise randomly arranged nanoparticles. In one embodiment, the at least one active material comprises randomly arranged nanoparticles. In one embodiment, the active material comprising a plurality of nanoparticles is located on the substrate.
  • the active material comprising a plurality of nanoparticles or the film of nanoparticles covers partially or totally the substrate.
  • the active material comprising a plurality of nanoparticles is located on the substrate and the first and second electrodes.
  • the active material comprising a plurality of nanoparticles covers partially or completely the first and second electrodes.
  • the active material comprising a plurality of nanoparticles is implemented into a film of nanoparticles.
  • the film of nanoparticles is obtained from colloidal nanoparticles.
  • the film of nanoplatelets is obtained from colloidal nanoplatelets.
  • the active material comprising a plurality of nanoparticles is continuous from the first electrode to the second electrode.
  • said nanoparticles are used in the manufacture of a film of nanoparticles.
  • said nanoparticles are used in the manufacture of a colloidal quantum dot film.
  • said nanoparticles are used in the manufacture of a quantum dot solid.
  • the active material comprising a plurality of nanoparticles has a thickness of the same order of magnitude as the absorption length of the plurality of nanoparticles.
  • the active material comprising a plurality of nanoparticles has a thickness from 10 nanometers to 1 centimeter.
  • the active material comprising a plurality of nanoparticles has a thickness from 10 nanometers to 10 micrometers.
  • the active material comprising a plurality of nanoparticles has a thickness from 10 nanometers to 1 micrometer. In one embodiment, the active material comprising a plurality of nanoparticles has a thickness from 10 nanometers to 900 nanometers.
  • the active material comprising a plurality of nanoparticles has a thickness from 10 nanometers to 800 nanometers.
  • the active material comprising a plurality of nanoparticles has a thickness from 10 nanometers to 700 nanometers. In one embodiment, the active material comprising a plurality of nanoparticles has a thickness from 10 nanometers to 600 nanometers.
  • the active material comprising a plurality of nanoparticles has a thickness from 10 nanometers to 500 nanometers. In one embodiment, the active material comprising a plurality of nanoparticles has a thickness from 10 nanometers to 400 nanometers.
  • the active material comprising a plurality of nanoparticles has a thickness from 10 nanometers to 300 nanometers.
  • the active material comprising a plurality of nanoparticles has a thickness from 10 nanometers to 200 nanometers.
  • the active material comprising a plurality of nanoparticles has a thickness from 10 nanometers to 100 nanometers.
  • the nanoparticles of the invention are 0D, ID, and 2D nanoparticles.
  • One of the drawbacks of the 0D nanoparticle is their very sparse density of state only made of dirac comb which can typically include 2 electrons per state.
  • 2D systems are much more promising due to their larger density of state. They are consequently better candidate than the 0D system to sustain large density charging.
  • the nanoparticles of the invention are for example nanocrystals, nanosheets, nanorods, nanoplatelets, nanoplates, nanoprisms, nanowalls, nanodisks, nanoparticles, nanowires, nanopowder, nanotubes, nanotetrapods, nanoribbons, nanobelts, nanowires, nanoneedles, nanocubes, nanoballs, nanocoils, nanocones, nanopillers, nanoflowers, quantum dots or combination thereof.
  • the nanoparticles of the invention have the shape of a sphere, a cube, a tetrahedron, a rod, a wire, a platelet, a tube, a cube, a ribbon, or mixture thereof. It is one aim of the present invention to provide a large density of state and a large porosity.
  • the nanoparticles of the invention are nanosheets and the plurality of nanosheets presents an optimum porosity with efficient trade-off between the porosity and the charge density.
  • the plurality of nanosheets comprises pores size inferior to 1000 nm, or inferior to 100 nm, or inferior to 50 nm, or inferior to 10 nm, or inferior to 5 nm, or inferior to lnm, or inferior to 0.5 nm, or mixture thereof.
  • the nanoparticles of the invention comprise a semi-conductor from group IV, group IIIA-VA, group IIA-VIA, group IIIA-VIA, group IA-IIIA-VIA, group IIA-VA, group IVA-VIA, group VIB-VIA, group VB-VIA, or group IVB-VIA.
  • the nanoparticles of the invention comprise a material MxEy, wherein:
  • M is Zn, Cd, Hg, Cu, Ag, Al, Ga, In, Si, Ge, Pb, Sb, Sn, Pd, Fe, Au, Ti, Bi, W, Mo, V or a mixture thereof;
  • E is O, S, Se, Te, N, P, As or a mixture thereof;
  • x and y are independently a decimal number from 0 to 5, at the condition that when x is 0, y is not 0 and inversely.
  • the material MxEy comprises cationic elements M and anionic elements E in stoichiometric ratio, said stoichiometric ratio being characterized by values of x and y corresponding to absolute values of mean oxidation number of elements E and M respectively.
  • the nanoparticles of the invention comprises a material MxNyEz, wherein:
  • M is selected from Zn, Cd, Hg, Cu, Ag, Al, Ga, In, Si, Sn, Ge, Pb, Sb, Sn, Pd, Fe, Au, Ti, Bi, W, Mo, V or a mixture thereof;
  • N is selected from Zn, Cd, Hg, Cu, Ag, Al, Ga, In, Si, Sn, Ge, Pb, Sb, Sn, Pd, Fe, Au, Ti, Bi, W, Mo, V or a mixture thereof;
  • E is selected from O, S, Se, Te, N, P, As or a mixture thereof; and x, y and z are independently a decimal number from 0 to 5, at the condition that when x is 0, y and z are not 0, when y is 0, x and z are not 0 and when z is 0, x and y are not 0.
  • the nanoparticles of the invention are made of a quaternary compound such as InAlGaAs, ZnAglnSe or GalnAsSb.
  • the nanoparticles of the invention comprise a material from Si, Ge, Sn, CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, HgS, HgSe, HgTe, PbS, PbSe, PbTe, CuInS 2 , CuInSe 2 , AgInS 2 , AgInSe 2 , CuS, Cu 2 S, Ag 2 S, Ag 2 Se, Ag 2 Te, InN, InP, InAs, InSb, In 2 S 3 , Cd 3 P 2 , Zn 3 P 2 , Cd 3 As 2 , Zn 3 As 2 , ZnO, A1N, A1P, AlAs, AlSb, GaN, GaP, GaAs, GaSb, FeS 2 , Ti0 2 , Bi 2 S 3 , Bi 2 Se 3 , Bi 2 Te 3 , MoS 2 , WS 2 , V0 2 , and alloys and mixture
  • the nanoparticles of the invention present a heterostructure, which means that the nanoparticles of the invention are partially coated by at least one layer of inorganic material.
  • the nanoparticles of the invention present a core/shell structure, i.e. the nanoparticles comprise a core and a shell of semiconducting material.
  • the nanoparticles of the invention have a core/shell structure, i.e. the core is totally coated by at least one layer of inorganic material.
  • the nanoparticles of the invention comprises a core totally coated by a first layer of inorganic material, said first layer being partially or totally surrounded by at least one further layer of inorganic material.
  • the core and the at least one layer of inorganic material are composed of the same material or are composed of different materials.
  • the core and the at least one layer of inorganic material may be a semi-conductor from group IV, group IIIA-VA, group IIA-VIA, group IDA- VIA, group IA-IIIA-VIA, group IIA-VA, group IVA-VIA, group VIB-VIA, group VB-VIA, or group IVB-VIA.
  • the core and the at least one layer of inorganic material may comprise a material MxEy, wherein:
  • M is Zn, Cd, Hg, Cu, Ag, Al, Ga, In, Si, Ge, Pb, Sb, Sn, Pd, Fe, Au, Ti, Bi, W, Mo,
  • E is O, S, Se, Te, N, P, As or a mixture thereof;
  • x and y are independently a decimal number from 0 to 5, at the condition that when x is 0, y is not 0 and inversely.
  • the core and the at least one layer of inorganic material comprise a material MxNyEz, wherein:
  • M is selected from Zn, Cd, Hg, Cu, Ag, Al, Ga, In, Si, Sn, Ge, Pb, Sb, Sn, Pd, Fe, Au, Ti, Bi, W, Mo, V or a mixture thereof;
  • N is selected from Zn, Cd, Hg, Cu, Ag, Al, Ga, In, Si, Sn, Ge, Pb, Sb, Sn, Pd, Fe, Au, Ti, Bi, W, Mo, V or a mixture thereof;
  • E is selected from O, S, Se, Te, N, P, As or a mixture thereof;
  • x, y and z are independently a decimal number from 0 to 5, at the condition that when x is 0, y and z are not 0, when y is 0, x and z are not 0 and when z is 0, x and y are not 0.
  • the core and the at least one layer of inorganic material are made of a quaternary compound such as InAlGaAs, ZnAglnSe or GalnAsSb.
  • the core and the at least one layer of inorganic material may be composed of a material from Si, Ge, Sn, CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, HgS, HgSe, HgTe, PbS, PbSe, PbTe, CuInS 2 , CuInSe 2 , AgInS 2 , AgInSe 2 , CuS, Cu 2 S, Ag 2 S, Ag 2 Se, Ag 2 Te, InN, InP, InAs, InSb, In 2 S 3 , Cd 3 P 2 , Zn 3 P 2 , Cd 3 As 2 , Zn 3 As 2 , ZnO, A1N, A1P, AlAs, AlSb, GaN
  • the nanoparticles of the present invention comprise metallic materials such as gold, silver, copper, aluminum, iron, platinum, lead, or palladium.
  • the nanoparticles of the present invention present a hetero structure comprising metallic materials and semiconductor materials.
  • the nanoparticle of the invention may be further surrounded by a "coat" of an organic capping agent.
  • the organic capping agent may be any materials, but has an affinity for the semiconductor surface.
  • the capping agent can be an isolated organic molecule, a polymer (or a monomer for a polymerization reaction).
  • organic capping agents are selected from trioctylphosphine oxide, organic thiols, amines, phosphines, carboxylic acids, phosphonic acids, sulfonic acids, trialkoxysilanes, alkyl and aryl halides; and mixtures thereof.
  • the nanoparticle of the invention may be further surrounded by a "coat" of an inorganic capping agent.
  • the inorganic capping agent comprises an inorganic complex, an extended crystalline structure, metals selected from transition metals, lanthanides, actinides, main group metals, metalloids and mixture thereof.
  • the inorganic capping agent comprises ionic salts.
  • the nanoparticles of the invention may be surrounded by a mixture of inorganic and organic capping agent.
  • the nanoparticles of the invention for use in a transistor, a phototransistor or photodetector are selected in the group comprising: CdSe, CdTe, CdS, HgTe, PbS, PbSe, PbTe and the core/shell structures such as CdSe/CdS, CdSe/CdZnS, CdTe/CdS/CdZnS, CdS/ZnS, PbS/CdS, PbSe/CdS.
  • the active material of the photodetector of the present invention comprises inorganic semiconductors, preferably crystalline inorganic semiconductors.
  • the active material of the photodetector of the present invention comprises core inorganic semiconductor or type I heterostructures.
  • the active material of the photodetector of the present invention comprises CdSe, CdS, CdTe, ZnS, ZnSe, PbS, PbSe, PbTe, HgS, HgSe, HgTe, InP, InAs, GaAs, and mixture thereof.
  • the active material of the photodetector of the present invention does not comprise amorphous nanoparticles, or type II heterostructures.
  • type II heterostructures may have looked appealing since they tend to help dissociate the electron hole pair at the nanoparticle level even in absence of electric field, once processed under the form of a film, the p part will behave as electron traps and the n part as hole traps, which is not desirable.
  • An example of these type II heterostructures is core-shell structure made of CdSe and CdTe.
  • the nanoparticles are not selected from PbS.
  • the nanoparticles are not selected from carbon-based nanoparticles such as carbon nanowires, carbon nanotubes (multi-walled or single- walled), graphene or combination thereof.
  • the nanoparticles are not selected from silicon nanoparticles such as silicon quantum dots or silicon nanowires.
  • the nanoparticles are not selected from silver nanowire mesh. In one embodiment, the nanoparticles are not selected from metal oxide such as titanium dioxide.
  • the nanoparticles are not selected from materials that can undergo an intercalation/de-intercalation reaction with lithium ions.
  • the nanoparticles are not selected from perovskite nanoparticles.
  • the nanoparticles of the present invention have at least one dimension having a size of about 0.3 nm to less than 1 ⁇ , about 0.5 nm to about 700 nm, about 1 nm to about 500 nm, about 1.5 nm to about 200 nm, about 2 nm to about 100 nm.
  • the nanosheets of the present invention have a thickness of about 0.3 nm to about 10 mm, about 0.3 nm to about 1 mm, about 0.3 nm to about 100 ⁇ nm, about 0.3 nm to about 10 ⁇ , about 0.3 nm to about 1 ⁇ , about 0.3 nm to about 500 nm, about 0.3 nm to about 250 nm, about 0.3 nm to about 100 nm, about 0.3 nm to about 50 nm, about 0.3 nm to about 25 nm, about 0.3 nm to about 20 nm, about 0.3 nm to about 150 nm, about 0.3 nm to about 10 nm, about 0.3 nm to about 5 nm.
  • the nanosheets of the present invention have a lateral dimensions (length and/or width) of at least 1.5 times its thickness.
  • the lateral dimensions of the nanosheet are at least 2, 2.5, 3, 3.5, 4.5, 5 times larger than the thickness.
  • the lateral dimensions of the nanosheet are from at least 0.45 nm to at least 50 mm. In one embodiment, the lateral dimensions of the nanosheet are from at least 2 nm to less than 1 m, from 2 nm to 100 mm, from 2 nm to 10 mm, from 2 nm to 1 mm, from 2 nm to 100 ⁇ , from 2 nm to 10 ⁇ , from 2 nm to 1 ⁇ , from 2 nm to 100 nm, from 2 nm to 10 nm.
  • the nanosheets of the invention has a quasi-2D structure. In one embodiment, the nanoparticles are coupled to a high mobility material.
  • the nanoparticles is mixed or blended with a high mobility material.
  • the plurality of nanoparticles forming the active material are bridging said at least two electrodes; and at least 2% of their projected areas are overlapping with the at least two electrodes (i.e. each of the nanoparticles of the plurality of nanoparticles has an overlap area with the at least two electrodes spaced by a nanogap higher than 2% of the area of each of said nanoparticles).
  • the plurality of nanoparticles bridging the at least two electrodes spaced by a nanogap have at least 5%, 10% or preferably 20%, of their projected surface overlapping with the at least two electrodes spaced by a nanogap. In one embodiment, the plurality of nanoparticles bridging the at least two electrodes spaced by a nanogap have at least 1% of their projected area overlapping with each of the at least two electrodes spaced by a nanogap (i.e. each of the nanoparticles of the at least one nanoparticle has an overlap area with each of the at least two electrodes spaced by a nanogap higher than 1% of the area of each of said nanoparticles).
  • the plurality of nanoparticles bridging the at least two electrodes spaced by a nanogap have at least 2.5%, 5% or preferably 10% of their projected surface overlapping with each of the at least two electrodes spaced by a nanogap.
  • the film of nanoparticles forming the active material and bridging the at least two electrodes spaced by a nanogap has at least 2% of its projected area overlapping with the at least two electrodes spaced by a nanogap (i.e. the film of nanoparticles has an overlap area with the at least two electrodes spaced by a nanogap higher than 2% of the area of said film).
  • the film of nanoparticles bridging the at least two electrodes spaced by a nanogap has at least 5%, 10% or preferably 20% of its projected surface overlapping with the at least two electrodes spaced by a nanogap.
  • the film of nanoparticles forming the active material and bridging the at least two electrodes spaced by a nanogap has at least 1% of its projected area overlapping with each of the at least two electrodes spaced by a nanogap (i.e. the film of nanoparticles has an overlap area with each of the at least two electrodes spaced by a nanogap higher than 1% of the area of said film).
  • the film of nanoparticles bridging the at least two electrodes spaced by a nanogap has at least 2.5%, 5% or preferably 10% of its projected surface overlapping with each of the at least two electrodes spaced by a nanogap.
  • the electrolyte has at least one common interface with at least part of the active material comprising a plurality of nanoparticles.
  • the electrolyte has only one common interface with at least part of the active material comprising a plurality of nanoparticles. In one embodiment, the matrix of the electrolyte is not mixed with at least part of the active material comprising a plurality of nanoparticles.
  • the matrix of the electrolyte is not mixed with the active material comprising a plurality of nanoparticles.
  • the matrix of the electrolyte is not mixed with the film of nanoparticles.
  • the matrix of the electrolyte remains outside of the active material.
  • the active material is not saturated by the electrolyte.
  • the electrolyte has a thickness from 10 nanometers to 1 centimeter, preferably from 500 nanometers to 2 millimeters, more preferably from 1 micrometer to 10 micrometers.
  • solid, polymer, gel, ion-gel or liquid electrolytes may be implemented, preferably a gel or solid electrolyte.
  • contact between the electrolyte and the first and second electrodes is prevented by the active material comprising a plurality of nanoparticles.
  • the at least one electrolyte can be in the form of an aqueous solution of a dissolved ionic chemical compound (or compounds), a non-aqueous solution of a dissolved ionic chemical compound (or compounds), a polymer electrolyte, a gel electrolyte, a solid electrolyte or a molten salt electrolyte.
  • the electrolyte comprises a matrix and ions.
  • the electrolyte comprises a polymer matrix.
  • the polymer matrix of the electrolyte comprises polystyrene, poly(N-isopropyl acrylamide), polyethylene glycol, polyethylene, polybutadiene, polyisoprene, polyethylene oxide, polyethyleneimine, polymethylmethacrylate, polyethylacrylate, polyvinylpyrrolidone, polypropylene glycol, polydimethylsiloxane, polyisobutylene, or a blend/multiblocks polymer thereof.
  • the electrolyte comprises ions salts.
  • the polymer matrix is doped with ions salts.
  • the electrolyte comprises material that contains mobile ions of lithium, sodium, potassium, ammonium, hydrogen, copper, silver or mixture thereof.
  • the electrolyte comprises polymers and glasses, including but not limited to PEG, PEO, PVDF, PET, PTFE, FEP, FPA, PVC, polyurethane, polyester, polyglycol, silicone, some epoxies, polypropylene, polyimide, polycarbonate, polyphenylene oxide, polysulfone, calcium magnesium aluminosilicate glasses, E-glass, alumino-borosilicate glass, D-glass, borosilicate glass, silicon dioxide, quartz, fused quartz, silicon nitride, silicon oxynitride, or mixture thereof.
  • the electrolyte comprises ionic liquid.
  • the polymer matrix and the ions are replaced by a polymerizable ionic liquid.
  • the electrolyte is transparent in a wavelength window compatible with the absorption spectrum of the plurality of nanoparticles.
  • Compatible means herein that the substrate is at least partly transparent in the range of wavelength wherein the plurality of nanoparticles is absorbing.
  • Partly transparent means herein that the substrate has a transmittance of at least 50%, preferably at least 75%, more preferably at least 90%.
  • the electrolyte is transparent in the visible, i.e. in a wavelength range from about 380 nanometers to about 750 nanometers.
  • the electrolyte is transparent in the ultraviolet range of wavelength, i.e. in a wavelength range from about 10 nanometers to about 380 nanometers. In one embodiment, the electrolyte is transparent in the infrared range of wavelength, i.e. in the wavelength range from about 750 nanometers to about 1 000 000 nanometers, preferably from about 750 nanometers to about 50 000 nanometers, more preferably from about 750 nanometers to about 3000 nanometers.
  • the substrate is partly transparent in the visible and/or in the ultraviolet range of wavelength and/or in the infrared range of wavelength.
  • the electrolyte transparency window is at least lnm large, preferably at least lOnm large and more preferably above 50nm large.
  • the electrolyte is transparent in two wavelength windows compatible with the absorption spectrum of the plurality of nanoparticles.
  • the electrolyte transparency window is made of several windows in order to fit the absorption spectrum of the multicolor detector, preferably of several narrow transparency windows i.e. of at most 50 nm large.
  • the nanoparticle surface chemistry is chosen to be a counterion of one of the ions of the electrolyte. In one embodiment, the nanoparticle surface chemistry is chosen so that the nanoparticles and the electrolyte can form a redox reaction.
  • At least one ion from the electrolyte can reversibly give one or more electron(s) to the active material as in redox based reactions.
  • pairs of nanoparticle surface chemistry/ion include but is not limited to: OH7Li + , OH7Na + , OH7K + , OH 7NH 4 + , OH /any ammonium ion, OH /any ionic liquid, 0 2 7Li + , O 2 7Na + , O 2 7K + , O 2 7NH 4 + , O 2 7any ammonium ion, O 2 7any ionic liquid, HS " /Li + , HS 7Na + , HS 7K + , HS 7NH 4 + , HS /any ammonium ion, HS /any ionic liquid, SCN /Li + , SCN7Na + , SCN7K + , SCN7NH 4 + , SCN7any ammonium ion, SCN7any ionic liquid, NH 2 7Li + , NH 2 7Na + , NH 2 7K +
  • dielectric constant and a DL is the width of the double layer formed at the electrolyte- active material interface.
  • This invention relates to a photodetector having an ultra large capacitance.
  • the electronic component preferably the photodetector, has a gate
  • the electronic component preferably the photodetector, has a gate capacitance superior to 30 ⁇ - ' 2 , from 30 to 105 ⁇ - ' 2 , preferably from 30 to
  • the electronic component preferably the photodetector, has a gate capacitance of at least 30 ⁇ - ' 2 , preferably at least 100 ⁇ - ' 2 , 200 ⁇ - ' 2 , 300 ⁇ "2 , 400 ⁇ 2 , 500 ⁇ . ⁇ 2 , 1000 ⁇ "2 , 1500 ⁇ 2 , 5000 ⁇ 2 , 10000 ⁇ "2 , 15000 ⁇ 2 .
  • the electronic component, preferably the photodetector, of the present invention presents good cycling properties above 100 cycles.
  • the electronic component preferably the photodetector, presents on/off ratio from 1 to 10 11 .
  • the electronic component preferably the photodetector, presents at room temperature subthreshold slope from 20mV/decade to 3V/decade, preferably from 50mV/decade to lV/decade, more preferably from 59 mV/decade to 600 mV/decade.
  • the photodetector presents a responsivity ranging from ⁇ . ⁇ '1 to 1MA.W “1 , preferably from ⁇ . ⁇ "1 to lkA.W -1 , more preferably from ImA.W "1 to lkA.W -1 .
  • the photodetector presents a detectvity ranging from 10 cm. Hz 1/2 W _1 (also named “Jones”) to 10 14 jones and more preferably from 10 8 jones to 10 13 jones.
  • ions from the electrolyte migrate at the interface between the electrolyte and the active material comprising a plurality of nanoparticles.
  • the ions from the electrolyte migrate within the active material comprising a plurality of nanoparticles.
  • bulk doping or bulk charging is achieved within the active material comprising a plurality of nanoparticles.
  • bulk doping or bulk charging is achieved within the film of nanoparticles.
  • charges are injected in the active material comprising a plurality of nanoparticles; the introduction of the ions induces indeed a charging of the quantum states of the nanoparticles.
  • the continuity of the active material comprising a plurality of nanoparticles prevents direct contact between the electrolyte and the first and second electrodes therefore preventing leakage through the dielectric.
  • the manufacturing process for preparing the electronic component, preferably the photodetector, of the present invention comprises three main steps:
  • the method for producing an electronic component preferably a photodetector, comprises:
  • step b') the deposition of the previous solution of nanoparticles, which will form the active material onto the electrodes and substrate, c') if step b') is not implemented, nanop article's ligand exchange step on the active material comprising a plurality of nanoparticles,
  • the at least first and second electrodes are fabricated using a lift-off procedure onto the substrate.
  • the source electrode and the drain electrodes may be deposited using conventional deposition techniques, including for example, drop casting, inkjet printing, screen printing, gravure printing, flexographic printing or any other means that a person skilled in the art would find appropriate.
  • thin metallic electrodes having a thickness from 1 to 40 nanometers, preferably from 10 to 30 nanometers are used.
  • metallic electrodes having a thickness from 1 to 1000 nanometers, preferably from 10 to 100 nanometers, more preferably from 20 to 75 nanometers are used.
  • the nanoparticles of the invention are dispersed in a solvent, such as for example a mixture of hexane and octane with a volume ratio of 9: 1, in order to obtain the solution of nanoparticles.
  • a solvent such as for example a mixture of hexane and octane with a volume ratio of 9: 1
  • the solution of nanoparticles of step b) is deposited during step c) onto the substrate.
  • the solution of nanoparticles of step b) is deposited during step c) onto the electrically insulating substrate and the first and second electrodes.
  • the solution of nanoparticles deposited during step c) comprises various nanoparticles.
  • the steps b), b'), c), c') may implemented more than once with various nanoparticles.
  • the electrodes are processed with a gas treatment before step c).
  • the electrodes are treated with molecules such as short- chain alkane thiols to improve the adhesion of the nanoparticles before step c). According to one embodiment, the electrodes are treated with a coating for passivating the surface of the at least two electrodes before step c).
  • the electrodes are annealed before step c) at a temperature ranging from 100°C to 1000°C.
  • the deposition of nanoparticles is achieved during step c) by sputtering techniques, evaporation techniques, electrophoretic deposition, vacuum methods, lithography process, spray pyrolysis, hot and cold plasma, inert gas phase condensation techniques or any other means that a person skilled in the art would find suitable.
  • the deposition of nanoparticles is achieved during step c) by drop casting, spin coating, dip coating, spray coating, screen printing, inkjet printing or any other means that a person skilled in the art would find appropriate.
  • the nanoparticles prepared in solution at step c) present wide or narrow band gap.
  • nanoparticle's ligand exchange is performed in the active material comprising a plurality of nanoparticles after deposition or on the nanoparticles in solution prior to the deposition, preferably in the active material comprising a plurality of nanoparticles after deposition.
  • nanoparticle's ligand exchange is performed in the active material comprising a plurality of nanoparticles after deposition or on the nanoparticles in solution prior to the deposition, preferably on the nanoparticles in solution prior to the deposition.
  • nanoparticle's ligand exchange is performed on the active material comprising a plurality of nanoparticles during step c'), for example by dipping the nanoparticles in a solution.
  • the nanoparticle's ligand exchange is performed directly in solution prior to the deposition of nanoparticles as in step b').
  • nanoparticle's ligand exchange improves the conduction properties of the active material.
  • the electronic component, preferably the photodetector, in progress is annealed before step d) at low temperature, typically below 400°C, or below 300°C or below 200°C, or below 100°C.
  • step d) the electrolyte is brushed on the active material comprising a plurality of nanoparticles.
  • the electrolyte is deposited using any printing methods that a person skilled in the art would find suitable, such as for example spin coating or dip coating, or drop casting.
  • the electrolyte is prepared by dissolving an ion salt and a polymer matrix in a polar solvent. In one embodiment, the electrolyte is prepared by melting ion salt in the polymer matrix at moderate temperature, typically 150°C.
  • the gate electrode deposited on the electrolyte during step e) is a metallic contact deposited by any methods that a person skilled in the art would find suitable such as for example drop casting or metal evaporation techniques.
  • the electronic components of the invention are particularly useful as transistor, photodetector or phototransistor.
  • the term phototransistor is used herein to describe a transistor device used as light detector.
  • the photodetector of the invention is a phototransistor.
  • the source electrode and the drain electrode are connected to opposite terminals of a common voltage source.
  • the gate electrode is connected to a second voltage source.
  • the transistor, the phototransistor and/or the photodetector are used as part of a global product.
  • the global product may comprise more than one transistor, phototransistor and/or photodetector.
  • the transistor of the present invention comprises at least three electrodes: a source electrode, a drain electrode and a gain electrode.
  • the transistor is an electrochemical transistor.
  • the transistor of the present invention comprises one drain electrode, one source electrode and two gate electrodes.
  • the charge density through the fourth gate can be modulated quickly.
  • the photodetector and/or the phototransistor device of the invention comprises at least 2, 3, 4 or 5 electrodes.
  • the phototransistor and/or photodetector comprises more than one active material. These active materials can be stacked or not.
  • the phototransistor and/or photodetector comprises two active materials, one p type and on n type. Each material can be independently addressed using the gate voltage as a switch.
  • the system can be used as a bicolor detector.
  • the phototransistor and/or photodetector comprises at least two active materials, with different band gap. Each material can be addressed by tuning the gate voltage.
  • the system can be used as a multicolor detector.
  • the active material used to build the phototransistor and/or photodetector is processed under a pixel form. In one embodiment, the active material used to build the phototransistor and/or photodetector is processed under an array of pixel.
  • the gate electrodes is grounded and a source and drain bias with different sign is applied.
  • the gate electrodes is grounded and a pn junction is formed between the drain and source.
  • a pn junction is formed between two of the electrodes and this photodetector is used as a LED or as a photodetector operating in photovoltaic mode.
  • the present invention also relates to an array comprising a plurality (i.e. at least two) of photodetectors and/or phototransistors of the present invention.
  • the array comprises a plurality of photodetectors or phototransistors and a readout circuit electrically connected to the plurality of photodetectors or phototransistors.
  • a single read out circuit is needed (i.e. the at least two active materials are addressed using the same drain source bias).
  • each photodetectors or phototransistors comprises a read-out circuit.
  • the active material used to build the phototransistor and/or photodetector is coupled to a readout circuit.
  • the present invention also relates to an imaging chips called focal plane array comprising the array of the present invention and optionally the readout circuit.
  • the focal plane array may be used in an imaging device.
  • At least one phototransistor and/or photodetector of the present invention is integrated into an imaging device such as a camera.
  • the invention can find applications in digital and analog switches, signal amplifiers, power regulators, equipment controllers and as building blocks of integrated circuits. In one embodiment, the invention can find applications in imaging sensors, remote sensing, night vision and ultra-low power detection.
  • Figure 1 illustrates the three different regimes of operation of the electronic component: a) on left the ion injection regime (low frequency regime), b) on middle the double electrostatic layer (intermediate frequency regime) and c) on right the high frequency mode where the electrolyte is used as a dielectric.
  • Figure 2 is a sectional view of an electronic component according to one embodiment of the present invention.
  • Figure 3 shows a sectional view of a detector structure according to one embodiment of the present invention.
  • Figure 4 shows a sectional view of an electronic component structure in one embodiment of the present invention, in a planar geometry.
  • Figure 5 shows a sectional view of an electronic component structure in one embodiment of the present invention, in a vertical geometry.
  • Figure 7 shows a curve comparing an electronic component of the present invention with the usual fabrication method. It shows drain source current as a function of the gate bias for a film of HgTe nanoparticles. Data for the film charged through the electrolyte (LiC10 4 in PEG 88k) and via a back gating through the Si02 layer of the substrate were plotted on the same graph.
  • Figure 8 illustrates the variation of the optical spectra of a film of PbS colloidal quantum dots at different charging time.
  • Figure 9 illustrates the cycling properties of an electronic component of the present invention. It shows drain source current as a function of the time while the gate bias is cycled for a film of CdSe/CdS nanoplatelets (electrolyte is LiC10 4 in PEG 6k). At each cycle a gate step crenel is applied from 0 to 2V. The drain source bias is lOmV.
  • Figure 10 illustrates the responsivity of a phototransistor made of CdSe-CdS core shell nanoplatelets as a function of gate bias.
  • Figure 11 illustrates a scheme of bicolor phototransistor using two pluralities of nanoparticles.
  • Figure 12 illustrates a scheme of phototransistor according to one embodiment of the present invention comprising a substrate, three electrodes: a source electrode (S), a drain electrode (D) and a gate electrode (G), a plurality of nanoparticles and an electrolyte (E).
  • S source electrode
  • D drain electrode
  • G gate electrode
  • E electrolyte
  • TMSS Bis(trimethylsilyl)sulfide
  • ODE octadecene
  • the solution is quickly cooled to room temperature.
  • the solution is precipitated by adding ethanol and centrifuged for 5min at 3000rpm.
  • the solid is redispersed in toluene.
  • the cleaning step is repeated a second time. At the third cleaning, selective precipitation is performed to separate the different size.
  • 0.44g of lead oxide is mixed in a three-neck flask with 2mL of oleic acid and lOmL of phenyl ether at 150°C under Argon for thirty minutes.
  • 32mg of sulfur flake are sonicated with 2mL of filtered oleylamine.
  • the obtained mixture is red- orange.
  • the flask is heated up to 190°C and the sulfur in oleylamine quickly injected.
  • the reaction is then conducted at 180°C for 5 minutes.
  • the cleaning process is done three times by adding ethanol/methanol as non-solvent and toluene as non-polar solvent.
  • trioctylphosphine selenide (TOPSe) is prepared by stirring Se powder in trioctylphosphine (TOP) at room temperature.
  • TOP trioctylphosphine
  • a three-neck flask 650mg of trihydrate lead(II) acetate Pb(Oac)2(H 2 0)3 are introduced with 2mL of phenyl ether, 1.5mL of oleic acid and 8mL of TOP.
  • the solution is degased, as well as a second flask only filled with lOmL of pure phenyl ether, for lhour at 85°C.
  • the one containing the lead precursor is cooled to 45°C and 1.7mL of the TOPSe solution is added.
  • the solution is kept under stirring condition for 5 extra minutes.
  • the content of the flask is introduced in a 20mL syringe.
  • the flask filled with just phenyl ether is heated up to 200°C under Argon.
  • the content of the syringe is quickly injected.
  • the Temperature of the flask cooled down to 140°C after the injection. During the next 90s the temperature is set at 120°C to avoid a too fast cooling. After this delay the flask is promptly cooled to room temperature.
  • the cleaning is operated in the first step by addition of methanol and ethanol. After centrifugation the solid is dispersed in toluene.
  • ethanol acetone/ethanol
  • trioctylphosphine telluride (TOPTe) is prepared by a slow stirring of Te powder in trioctylphosphine (TOP).
  • TOP trioctylphosphine
  • 135mg of HgCl 2 and 7.4g of octadecylamine are degased under vacuum for lhour at 120°C.
  • the atmosphere is then switch to Argon and the solution heated at 80°C.
  • 0,5ml of the 1M TOPTe are quickly injected and the reaction is performed at the same temperature for 5min.
  • the solution is quenched by a quick addition of dodecanthiol. Finally the flask is cooled down to room temperature.
  • Cadmium myristate (Cd(Myr) 2 ) is prepared.
  • Cd(Myr) 2 25mg Se powder are mixed in 30ml of ODE, the solution degased under vacuum for 20min at room temperature. Then the atmosphere is switch to Argon and the temperature is set to 240°C.
  • 204°C 40mg of Cd(OAc) 2 are quickly added.
  • the reaction is performed 12min at 240°C. 1ml of oleic acid is quickly injected to quench the reaction and the solution is cooled down.
  • the precipitation of the nanoplatelets is done by adding ethanol. After centrifugation the obtained solid is redispersed in hexane. The cleaning procedure is repeated three times.
  • NMFA N methyl formamide
  • 30mg of NaSH are mixed in 4 ml of N methyl formamide (NMFA) in a 20mL vial up to dissolution.
  • 500 ⁇ of the CdSe core in solution in hexane are added in the vial.
  • the solution is stirred until a complete transfer of the nanoparticles in the NMFA phase.
  • 500 ⁇ 1 of 0.2M cadmium acetate in NMFA are added in the vial.
  • the reaction is performed for lhour at room temperature under stirring. Precipitation is ensured by addition of ethanol. After centrifugation the obtained solid is dispersed in NMFA.
  • the cleaning step is repeated a second time.
  • Cadmium propanoate (Cd(Prop) 2 ) is prepared by mixing 1.036g of CdO in 10ml of propionic acid under Argon for 1 hour. Then the flask is open to air and the temperature risen to 140°C up to the point the volume get divided by a factor two. The whitish solution is precipitated by addition of acetone. After centrifugation the solid is dried under vacuum for 24 hours.
  • TOPTe is prepared by stirring 2.55g of Te pellets in 20ml of TOP for four days at room temperature.
  • the electrolyte is a mixture of polyethylene glycol (PEG) or polyethylene oxide (PEO) with a given molar weight and ions.
  • PEG polyethylene glycol
  • PEO polyethylene oxide
  • the molar ratio between the cation and the oxygen is taken equal to 16.
  • 50mg of L1CIO 4 and 230mg of PEG are heated together at 150°C on a hot plate in the glove box.
  • PEG/PEO molar weight the mixture is heated at 200°C. Processing the electrolyte in air has not lead to any noticeable change.
  • the electrolyte may also be prepared in an alternative way.
  • the goal of this change is to initially have a liquid electrolyte which can be deposited in a thinner film compared to what can be achieved with solventless preparation.
  • 250mg of L1CIO 4 1.15g of PEG 88k and 3g of acetonitrile are stirred in a 20mL vial, up to obtain a clear solution.
  • Electrodes are fabricated using a regular lift-off procedure onto a Si/Si02 wafer with an oxide thickness of 500nm. A thermal evaporation of Cr (2.5nm) and gold (17.5nm) is used for the contact. Electrodes are composed of 25 interdigitated pairs which are 2.5mm long. Two sets of electrodes have been designed with a spacing of 10 and 20 ⁇ . The W/L ratio is 6250 for the ⁇ spaced electrodes and 3125 for the 20 ⁇ spaced electrodes.
  • the nanoparticles are dispersed in a mixture of hexane and octane (9: 1 as volume ratio).
  • the electrodes are warmed at 125°C on a hot plate for two minutes and then thermalized at room temperature.
  • the solution is dropcasted onto the interdigitated electrodes.
  • the typical thickness for a film is 30nm.
  • the film is then rinsed in pure ethanol.
  • the film is annealed at 80°C for one minute.
  • NMFA N methyl formamide
  • This solution is dropcasted on the electrodes on a hot plate at 100°C.
  • the heating is performed 10 minutes more than requested to dry the film.
  • the typical thickness for a film is 40nm.
  • the electrolyte is softened by warming it on a hot plate at 80°C.
  • the electrolyte is brushed on the film of nanoparticles processed with the S " ligand exchange. Typical thickness is around 1mm.
  • the device is finally degased under vacuum for at least 20min at room temperature. Finally a metallic contact is deposited on the electrolyte as a gate electrode.
  • the system is the same as described in 5. but the substrate is a two layers system composed a conductive layer such as doped Si and a dielectric (insulating) layer such as Si0 2 , Hf0 2 or non-conductive polymer.
  • the system is a four electrodes terminal comprising: one drain and one source to bias the channel made of the nanoparticles, one gate electrodes to connect the electrolyte and one substrate electrode to connect to the conductive layer of the substrate.
  • the gate electrodes is used to strongly modulate the carrier density, while the substrate electrode is used to obtain a fast carrier density modulation.
  • the electrodes are deposited on a transparent substrate at the wavelength of detection such as glass in the visible or Si in the mid IR.
  • the nanoparticle film can be obtained using a multilayer approach. The film deposition and ligand exchange steps are repeated several times, up to the point where the film thickness reach the desired value, typically in the 30nm to 3 ⁇ range. 5b-2. Phototransistor preparation with CdSe quantum dots
  • the electrolyte is softened by warming it on a hot plate at 100°C.
  • the nanoparticles are capped with S " ligands with one of the method describe is example 4.
  • Electrodes are prepared on glass substrate according to the method of example 3.
  • the nanoparticle solution is dropcasted on the electrodes on a hot plate at 100°C and then annealed quickly at 220°C for 2 min in a Ar filled glove box.
  • the electrolyte is brushed on the film of nanoparticles processed with the S " ligand exchange. Typical thickness for the electrolyte is around 1mm.
  • the device is finally let cooled down to room temperature either under vacuum or under inert atmosphere. Finally a metallic contact is deposited on the electrolyte as a gate electrode. 5b-3. Phototransistor preparation with CdSe/CdS nanoplatelets
  • the electrolyte is softened by warming it on a hot plate at 100°C.
  • the nanoparticles are capped with S " ligands with one of the method describe is example 4.
  • Electrodes are prepared on glass substrate according to the method of example 3.
  • the nanoparticle solution is dropcasted on the electrodes on a hot plate at 120°C and then annealed quickly at 200°C for 2 min in a Ar filled glove box.
  • the electrolyte is brushed on the film of nanoparticles processed with the S " ligand exchange. Typical thickness for the electrolyte is around 1mm.
  • the device is finally let cooled down to room temperature either under vacuum or under inert atmosphere. Finally a metallic contact is deposited on the electrolyte as a gate electrode.
  • the electrolyte is softened by warming it on a hot plate at 100°C.
  • the nanoparticles are capped with S " ligands with one of the method describe is example 4.
  • Electrodes are prepared on sapphire substrate according to the method of example 3.
  • the nanoparticle solution is dropcasted on the electrodes on a hot plate at 80°C and then annealed quickly at 100°C for 2 min in a Ar filled glove box.
  • the electrolyte is brushed on the film of nanoparticles processed with the S " ligand exchange. Typical thickness for the electrolyte is around 1mm.
  • the device is finally let cooled down to room temperature either under vacuum or under inert atmosphere. Finally a metallic contact is deposited on the electrolyte as a gate electrode.
  • the electrolyte is softened by warming it on a hot plate at 100°C.
  • the nanoparticles are capped with S " ligands with one of the method describe is example 4.
  • Electrodes are prepared on undoped silicone substrate according to the method of example 3.
  • the nanoparticle solution is dropcasted on the electrodes on a hot plate at 80°C and then annealed quickly at 100°C for 2 min in a Ar filled glove box.
  • the electrolyte is brushed on the film of nanoparticles processed with the S " ligand exchange. Typical thickness for the electrolyte is around 1mm.
  • the device is finally let cooled down to room temperature either under vacuum or under inert atmosphere. Finally a metallic contact is deposited on the electrolyte as a gate electrode.
  • the electrolyte is softened by warming it on a hot plate at 100°C.
  • the nanoparticles are capped with S " ligands with one of the method describe is example 4.
  • Electrodes are prepared on quartz substrate according to the method of example 3.
  • the nanoparticle solution is dropcasted on the electrodes on a hot plate at 120°C and then annealed quickly at 250°C for 2 min in a Ar filled glove box.
  • the electrolyte is brushed on the film of nanoparticles processed with the S " ligand exchange. Typical thickness for the electrolyte is around 1mm.
  • the device is finally let cooled down to room temperature either under vacuum or under inert atmosphere. Finally a metallic contact is deposited on the electrolyte as a gate electrode.
  • a solution of poly(3-hexylthiophene) (P3HT) is prepared by mixing 30mg/ml of P3HT solid in chloroform. In the upper area the P3HT solution is deposited (p type layer) on the electrodes on a hot plate at 100°C. Once the system is dried CdSe/CdS nanoplatelets (n type layer) are deposited using the same process on the lower area of the electrodes. The electrolyte is then brushed on the whole device. Depending on the sign of the gate bias, only the p or n layer leads to a significant contribution to the current.
  • Interdigitated electrodes (0.3cm ) prepared on transparent substrate at the two wavelength which aim to be detected are used as substrate.
  • a solution of HgTe quantum dot dispersed in hexane:octane (9: 1 as volume ratio) is dropcasted on one of the electrode.
  • CdSe/CdS nanoplatelets are deposited by dropcatsing on a hot plate at 100°C.
  • the electrolyte is then brushed on one of the two pair of electrodes. Then the two pair of electrodes are electrically connected to obtain one source and one drain electrode.
  • the gate bias is used to tune the gain of the nanoplatelets film.
  • a phototransistor according to the present invention is characterized under the following condition. CdSe/CdS nanoplatelets coated with S " capping ligands have been deposited on interdigitated drain source electrodes. The measurements are made at room temperature under secondary vacuum. The applied drain source is 1 V. The applied gate bias is 1 V. The sample is illuminated using a 405 nm with a power between 1 and 50 mW. The obtained photoresponse is ranging from 1 to 10 mA.W "1 . Pn junction formation
  • HgTe quantum dots are capped using S " ligands, using a phase transfer method using Na2S precursor dissolved in N-methyl formamide.
  • the nanoparticle solution is dropcasted on electrodes.
  • a gate electrode is deposited on the electrolyte and grounded.
  • a source bias of 2V compared to the gate is applied and a drain bias of -2V compared to the gate is also applied while using a two channel sourcemeter.
  • the whole system is frozen by cooling the system to a temperature below the freezing point of the electrolyte. Then a stable pn junction is formed showing a current-voltage characteristic of a diode.

Abstract

The present invention relates to a photodetector comprising a substrate, at least three electrodes, an active material comprising a plurality of inorganic semiconductor nanoparticles bridging at least two electrodes and an electrolyte. An aspect of the invention is also to provide a manufacturing process and the use of said photodetector.

Description

LARGE CAPACITANCE ELECTRONIC COMPONENTS
FIELD OF INVENTION
The present invention relates generally to electronic components. More particularly, this invention relates to transistors, photodetectors and photo transistors. This invention also relates to the manufacturing process and the use of said electronic components.
BACKGROUND OF INVENTION
A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power. The transistor is the fundamental building block of modern electronic devices, and is ubiquitous in modern electronic systems.
The field effect transistor (FET) has been introduced as a system to tune the conductance of a material, that we will name "the active material", through the modulation of its charge-carrier density. The active material is in general a semiconductor. It can be a single crystal obtained by top-down methods, thin film techniques, molecular beam epitaxy, or molecular organic chemical vapor deposition. It can also be obtained using the assembly of crystalline nanoparticles.
Usually a FET is a three electrodes device where a first electrode, the gate electrode, is used to control the carrier density of the channel connecting the two other electrodes: the drain and the source electrodes.
The good performances of a FET rely in the optimization of two parameters: the conductivity of the active material, and the charge density that can be achieved in the active material. In the case of FET with an active material obtained from an assembly of nanoparticles, which offers extremely easy and cheap process compatible with flexible electronics, the main efforts have been geared toward the enhancement of the active material conductivity, with recent great success. The charge density of the active material has remained comparatively poor, and its modulation is classically limited to the interface of the active material and the dielectric.
For regular FET, a typical strategy is to use a Si/Si02 substrate, where the silica layer is used as a dielectric layer. Application of a bias over the oxide capacitively induces charges at the surface of the oxide. If nanoparticles are deposited on the surface it is possible to induce a change of the carrier concentration. Indeed the surface capacitance is given by wherein £Q is the vacuum permittivity, ετ is the relative
Figure imgf000003_0001
dielectric constant of the dielectric layer and t is the thickness of dielectric.
Two strategies can be used to increase the capacitance (i) an increase of the dielectric constant which can be obtained through the use of high-k material like Hf02, or (ii) a reduction of the dielectric thickness. The latter approach results in a trade-off between a higher capacitance and an increase of the gate current leakage. Nevertheless such an approach leads to a limited charge density, typically below 10 13 cm -"2. Alternative strategies have been developed to overcome this limitation, for instance using electrolytic FETs.
Electrolytic field effect transistors are typically composed successively of a substrate, two electrodes, a layer of active material, a liquid or solid electrolyte and a third electrode. A voltage or current applied to one pair of the transistor's electrodes, the control electrodes, changes the current flowing through another pair of terminals, the controlled current. Since solid state FETs remain limited to the low charging domain, many efforts have been devoted to try to improve the charging through the combined use of liquid electrolyte and colloidal nanoparticles, as described for instance in electro chromic nanocrystal quantum dots, Science 291, 2390 (2001) or electrochemical gating: a method to tune and monitor the (opto)electronic properties of functional materials, Electrochimica Acta 53, 1140 (2007). These electrolytic FETs have higher charge density than regular FET. However this higher charge density is obtained by using liquid electrolyte, which presents the disadvantage of possible leakage of the electrolyte in the system. Moreover the system is generally quite bulky, and no clear evidence of size reduction has been obtained so far. In order to try to overcome these difficulties, the use of solid electrolyte has been reported. The use of electrolyte polymer allows an easy fabrication and a large current modulation, while the solid aspect allows a better integration of the system and consequently a size reduction. For instance, Moon Sung Kang, and C. Daniel Frisbie describe in Size dependent electrical transport in CdSe nanocrystal thin film, Nano Lett. 10, 3227 (2010) or in High Carrier Densities Achieved at Low Voltages in Ambipolar PbSe Nanocrystal Thin-Film Transistors, Nano Lett 9, 3848 (2009) the use of semiconductor nanocrystals in electronic devices, especially transistors. Thin film transistors using a film of CdSe nanocrystals have been tested. The polarization of the electrolyte induces a build-up of charge carriers near the interface of the semiconductor layer and the electrolyte. This has led to gate capacitance up to 22μ¥θΏί 2. This value was the highest obtained so far, and is consistent with a charging of the active material only at the interface with the electrolyte matrix.
Other examples of FET with nanoparticles as an active material can be found, such as the one proposed in the United States patent application US 2010/0308299. However the charge densities modulation of the active materials is limited to the interface between the dielectric and the active materials, without charging in the whole volume of the active material. In US 2010/0308299, an electronic component comprising two electrodes, a layer of nanoparticles and a dielectric layer having at least one common interface with at least a part of the nanoparticles is described. The layer of nanoparticles includes an electronically conducting compound of a metal and an element of group VI of the periodic table. In this patent application, the device comprises a highly conducting channel at zero applied voltage at the gate, which generates useless energy consumption in the off state which is not the case in the current invention. Moreover the tuning of the conductance under a gate bias remains limited to a factor of 350 in US 2010/0308299.
On the contrary to these examples, the applicant has discovered that, in the electronic components of the present invention, ions from the electrolyte can migrate within the bulk of the active material, although the polymer matrix supporting the electrolytes does not penetrate into the active material. This ion migration comes with a bulk charge of the active material and gives charge densities that are increased by several orders of magnitude. So the present invention aims at describing a new family of transistors having improved characteristics and high gain i.e. with a large-current variation of the controlled current resulting from a small variation of the voltage applied to the control electrodes. These improved characteristics results from the fact the active material can be charged in its entire volume, and not only at the interface with the dielectric. This modulation in the entire volume of the active material gives access to high charge densities that cannot be obtained with the classical FET. It is therefore an object of the present invention to elaborate an electronic component which takes full advantage of the large capacitance induced by the bulk doping or charging of the active material.
The general approach to describe the active material charging process through an electrolyte relies either on the formation of a double ionic layer at the interface between the electrolyte and the active material, or through redox processes at the surface of the active material. For example in an n-type material, cations from the electrolyte will densely accumulate at the surface (but still in the electrolyte) and will face a negatively charged layer of semiconductor. Moreover in the electrolyte a layer of anions comes on the top of the cations layer to screen them and lead to a null electric field in the bulk of the electrolyte. The charging of the semiconductor occurs through the injection by the source electrodes of electrons. As explained hereabove, so far this process leads to a
<DL _ F c r c F0
limited interface capacitance which value is UDL wherein o is the vacuum permittivity, ε r is the electrolyte dielectric constant and a°L is the width of the double layer.
The key advantage to use electrolyte is their ability to charge a nanomaterial into the full volume of the film by letting the ions percolate into the void of the film.
In a field effect transistor the current is given by
Vm -Vt
l(VDs ,VGS ) = Idark {VDS ,V( 1 + 10 , where S is the subthreshold slope and Vt the threshold voltage. Under illumination, an excess of charges, ? [s photogenerated and the effective bias driving the transistor becomes G , where G is the gate capacitance.
ent becomes:
Figure imgf000006_0001
with E the applied electric field over drain source and μ the carrier mobility. The excess εΝστώ
An = - of charge is given by the expression ph where e the proton charge, N the total number of nanoplatelets absorbing, σ the cross section of the particle, τ the minority carrier lifetime into the film, ^ the power flux per unit area and ^ph the energy of the incident photon.
The last term of equation (1) corresponds to the photocurrent in the photoconductive mode, but the enhanced photoresponse is related to the term 10 s
The responsivity of a light detector is defined as the ratio of the photogenerated current over the photon flux. It describes the ability of a material to convert light in an electrical signal. The more electrons generated per absorbed photon, the higher the performance. To enhance the number of photogenerated electron people have used optical process such as multiexciton generation or electrical process such as avalanche process. In the current invention we want to use the electrolyte transistor as possible strategy to tune the nanoparticle film responsivity. The change in the responsivity (R) compared to the regular photodetector (Rdet) is given by
An
R - R —^ = i .daAvDS,vGS = o _v) -io s 10^
^det Αη · μ · ΕΛ
εΝστφ
An · μ · E
Dark current enhancement
Photoresponse enhancement (2) One of the aims of this invention is to take advantage of the photoresponse enhancement brought by the gating and in particular the strong non linearity of the current with the carrier density. Typically the current invention will be operated at a bias close to the turn on voltage of the device, where the device remains poorly conductive in the dark. The excess of charge photogenerated will consequently lead to a rise of the current which is more important than the one obtained in absence of gating.
Within the present invention the photoconduction properties of colloidal nanoparticles is combined with the electrolyte gating to enhance the optoelectronic properties of the electronic component. The present invention is applicable to transistors and to photodetection devices, such as for example photo transistors.
Photodetector or phototransistor generates a photocurrent under light illumination. The present invention allows developing photodetector operating as a phototransistor, which takes full advantage of the current non-linearity with the nanoparticle charging. Phototransistor based on colloidal nanoparticles remains mostly undeveloped since usual transistor based on back-gating through a solid dielectric can only charge a thin layer of quantum dot (tens of nanometer), while photodetection generally request thicker film (several hundred nanometer) in order to absorb a significant part of the incident light. Moreover the fact that bulk doping of the active material can be achieved in the current invention is a key advantage. Another strong improvement of our technology compared to existing devices is the fact that ion gel polymer allows a drastic size reduction of the device compared to liquid electrolyte gating.
The invention is also based on the implementation of the right pair of nanoparticles surface chemistry/electrolyte. It is therefore another object of the present invention to elaborate an electronic component which takes full advantage of the optimized surface chemistry of the active material and which coupled the surface chemistry with a chosen electrolyte. Said electronic component of the invention can thus provide a high current modulation thanks to the volume charging of the active material. SUMMARY
This invention relates to a photodetector comprising a substrate, at least three electrodes, an active material comprising a plurality of inorganic semiconductor nanoparticles bridging at least two electrodes and an electrolyte. According to one embodiment, the substrate and/or the electrolyte are transparent in at least a wavelength window compatible with the absorption spectrum of the plurality of nanoparticles.
According to one embodiment, said nanoparticles are nanocrystals, nanosheets, nanorods, nanoplatelets, nanoparticles, nanowires, nanopowders, nanotubes, nanotetrapods, nanoribbons, nanocubes, quantum dots and/or combinations thereof.
According to one embodiment, said electrolyte is liquid, polymer, ion-gel or solid.
According to one embodiment, said photodetector is a phototransistor.
According to one embodiment, the at least two electrodes bridged by a plurality of inorganic semiconductor nanoparticles are spaced by a nanogap whose size ranges from 1 nanometer to 1 micrometer.
According to one embodiment, said photodetector comprises at least two pluralities of various nanoparticles which can be independently addressed using the gate voltage as a switch. In this embodiment, a bicolor or multicolor photodetector or phototransistor is achieved and the gate bias may tune the photocurrent spectrum. According to one embodiment, bulk charging is achieved within said active material comprising a plurality of nanoparticles.
According to one embodiment, said active material comprising a plurality of nanoparticles has a thickness from 10 nanometers to 1 centimeter, preferably from 10 nanometers to 10 micrometers, more preferably from 10 nanometers to 1 micrometer. This invention also relates to a method for producing a photodetector, the method comprising: a) the deposition of the first and the second electrodes onto a substrate, b) the preparation of a solution of nanoparticles,
b') a nanoparticle's ligand exchange step in solution,
c) the deposition of the previous solution onto the electrodes and substrate, c') if step b') is not implemented, nanoparticle's ligand exchange step on the active material comprising a plurality of nanoparticles,
d) the electrolyte deposition on the active material comprising a plurality of nanoparticles,
e) the third electrode deposition on the electrolyte. According to one embodiment, the deposition of nanoparticles is achieved by drop casting or spin coating, dip coating, spray casting, screen printing, inkjet printing, sputtering techniques, evaporation techniques electrophoretic deposition, or vacuum methods.
This invention also relates to a photodetector operating as in photovoltaic mode or a LED, comprising the photodetector as disclosed herein, wherein a pn junction is formed between two of the electrodes.
This invention also relates to an array comprising a plurality of photodetectors according to the present invention.
According to one embodiment, a readout circuit is connected to the plurality of photodetectors.
According to one embodiment, the plurality of photodetectors comprises a first plurality of photodetectors and a second plurality of photodetectors and wherein the band gap of the first plurality of photodetectors is different from the band gap of the second plurality. This invention also relates to a focal plane array for use in an imaging device comprising an array of photodetectors according to the present invention. DEFINITIONS
In the present invention, the following terms have the following meanings:
- As used herein the singular forms "a", "an", and "the" include plural reference unless the context clearly dictates otherwise. - The term "about" is used herein to mean approximately, roughly, around, or in the region of. When the term "about" is used in conjunction with a numerical range, it modifies that range by extending the boundaries above and below the numerical values set forth. In general, the term "about" is used herein to modify a numerical value above and below the stated value by a variance of 20 percent, preferably of 5 percent.
- "Active material" refers to the compound (usually a semiconductor) that bridges the source electrode and the drain electrode. In a field effect transistor the conductivity of the active material can be modulated with a gate electrode. In a phototransistor, the conductivity of the active material is tuned with the gate voltage so that the conductivity of the active material increases non-linearly with the absorption of photons.
- "Charged in volume" refers to a process by which the capacity of the plurality of nanoparticles forming the active material increases linearly with the film thickness, even if the electrolyte matrix is limited at the interface of the top of the nanoparticles' film, and does not permeate into the film.
- "Double layer" refers to a structure which describes the variation of electric potential near an interface. If a material is in contact with an electrolyte, a single layer of negative or positive ions from the electrolyte will form in close proximity to the material and a second layer with a preponderance of respectively positive or negative ions will form proximate the aforementioned respectively negative or positive ions forming the so-called double layer.
- "Film" refers to a single or multiple layers or coating of thin-or thick-material. In the present invention, a film is a porous or not, ordered or not, assembly of nanoparticles, which may be flat or rough. - "Nanoparticle" refers to a particle of any shape having at least one dimension in the 0.1 to 100 nanometers range.
DETAILED DESCRIPTION This invention relates to an electronic component which comprises a substrate, at least a first and a second electrodes, an active material comprising a plurality of nanoparticles and an electrolyte.
In one embodiment, the present invention provides an electronic component which comprises a substrate, at least three electrodes, an active material comprising a plurality of nanoparticles and an electrolyte.
In one embodiment, the electronic component of the invention is a photodetector.
In a preferred embodiment, the present invention provides a photodetector which comprises a substrate, at least three electrodes, an active material comprising a plurality of nanoparticles and an electrolyte. In one embodiment, the active material comprising a plurality of nanoparticles is implemented into a film of nanoparticles.
In one embodiment, the substrate or body may be formed from silicon, silicon dioxide, aluminum oxide, sapphire, germanium, gallium arsenide, an alloy of silicon and germanium, indium phosphide, indium tin oxide, fluorine doped tin oxide, graphene, glass and its derivative, plastic material or any material that a person skilled in the art would find suitable.
In another embodiment, the substrate is made of a plastic substrate coated with a conducting material, such as indium tin oxide coating on polyethylene terephthalate.
In another embodiment, the substrate may be form from ZnS, ZnSe InP, CdZnTe, ZnTe, GaSb, or mixture thereof. In one embodiment, the substrate may comprise an oxide layer acting as an electronic insulator.
In one embodiment, the substrate may comprise several layers with an oxide layer on the top, such as for example a Si02 layer on a Si layer. In one embodiment, the thickness of the oxide layer is from 10 nanometers to 100 micrometers, preferably from 30 nanometers to 1 micrometer, more preferably from 100 nanometers to 1 micrometer.
In one embodiment, the substrate may be rigid or non-rigid. According to a preferred embodiment, the substrate is rigid. According to another embodiment, the substrate is flexible and/or stretchable.
In one embodiment, the substrate is transparent.
In one embodiment, the substrate is transparent in a wavelength window compatible with the absorption spectrum of the plurality of nanoparticles. Compatible means herein that the substrate is at least partly transparent in the range of wavelength wherein the plurality of nanoparticles is absorbing. Partly transparent means herein that the substrate has a transmittance of at least 50%, preferably at least 75%, more preferably at least 90%.
In one embodiment, the substrate is transparent in the visible, i.e. in a wavelength range from about 380 nanometers to about 750 nanometers. In one embodiment, the substrate is transparent in the ultraviolet range of wavelength, i.e. in a wavelength range from about 10 nanometers to about 380 nanometers.
In one embodiment, the substrate is transparent in the infrared range of wavelength, i.e. in the wavelength range from about 750 nanometers to about 1 000 000 nanometers, preferably from about 750 nanometers to about 50 000 nanometers, more preferably from about 750 nanometers to about 3000 nanometers. According to one embodiment, the substrate is partly transparent in the visible and/or in the ultraviolet range of wavelength and/or in the infrared range of wavelength.
In one embodiment, the substrate transparency window is at least lnm large, preferably at least lOnm large and more preferably above 50nm large. In one embodiment, the substrate is transparent in two wavelength windows compatible with the absorption spectrum of the plurality of nanoparticles.
In one embodiment, the substrate transparency window is made of several windows in order to fit the absorption spectrum of the multicolor detector, preferably of several narrow transparency windows i.e. of at most 50 nm large. In an embodiment, the electronic component, preferably the photodetector, of the present invention comprises another substrate opposite to the first substrate.
In one embodiment, the electronic component of the present invention comprises 2 electrodes.
In a preferred embodiment, the electronic component of the present invention comprises 3 electrodes.
In one embodiment, the electronic component of the present invention comprises 4 electrodes.
In one embodiment, the electronic component, preferably the photodetector, of the present invention comprises enough electrodes to build a focal plane array where the active component is the current invention.
In one embodiment, a first and a second electrodes act as source and drain for the electronic component, preferably the photodetector.
In one embodiment, a first and a second electrode, preferably the source and drain electrodes, are interdigitated. In one embodiment, the source and the drain electrodes are located on the substrate. In one embodiment, the source and the drain electrodes are located on the active material comprising a plurality of nanoparticles.
In one embodiment, the active material is located between the source and the drain electrodes thereby bridging said two electrodes.
In one embodiment, the electronic component, preferably the photodetector, comprises a source electrode; a drain electrode disposed so as to be separated from the source electrode, forming a gap between the source and drain electrodes; an active material bridging the gap between the source and drain electrodes and thus forming a transistor channel; and a gate electrode positioned so as to be separated from the source electrode, the drain electrode and the semiconductor layer; wherein an electrolyte is disposed so as to contact at least a part of both the gate electrode and the active material.
In one embodiment, the electronic component, preferably the photodetector, comprises a third electrode, which acts as the gate.
In one embodiment, the gate electrode is located on the electrolyte. In one embodiment, the gate electrode is located on the substrate.
In one embodiment, the electronic component, preferably the photodetector, comprises a fourth electrode, which acts as the substrate electrode.
In one embodiment, the fourth electrode is located on the back of the substrate.
In one embodiment, at least one of the electrodes has a thickness from 1 to 1000 nanometers, preferably from 10 to 100 nanometers, more preferably from 20 to 75 nanometers.
In one embodiment, at least one of the electrodes comprises an electrochemically inert material such as for example gold, platinum, palladium, silver.
In one embodiment, at least one of the electrodes comprises any suitable conductive material such as for example gold, silver, copper, chromium, lithium fluoride, titanium, aluminum, silicon, magnesium, indium and conductive alloys. In one embodiment, at least one electrode is formed form transparent conducting layer made for example from transparent conducting oxides such as indium tin oxide, fluorine doped tin oxide, zinc oxide, doped zinc oxide.
In one embodiment, at least one of the electrodes is a doped semiconductor.
In one embodiment, at least one of the electrodes comprises nanoparticles of the same nature as the nanoparticles of the active material comprising a plurality of nanoparticles.
In one embodiment, at least one of the electrodes is a carbon based electrode, a graphite electrode, a graphene electrode, an electrode comprising carbon nanotube, or a metal electrode coated with carbon.
In one embodiment, at least one of the electrodes is a metal foil or any material that has been metalized previously.
In the present invention, conductive layer has the same meaning as electrode.
According to one embodiment, at least two electrodes are spaced by a nanogap. In a preferred embodiment, two of the three electrodes, preferably the source and drain electrodes, are spaced by a nanogap.
According to one embodiment, the size of said nanogap (i.e. the inter-electrodes distance) ranges from 0.1 nanometer to 1 000 nanometers, preferably from 0.1 nanometer to 200 nanometers, more preferably from 3 nanometers to 100 nanometers.
According to one embodiment, the depth of said nanogap ranges from 0.1 nm to 10 μιη, preferably from 0.1 nm to 1 μιη, more preferably from 1 nm to 100 nm.
According to an embodiment, the length of said nanogap ranges from 1 nanometer to 10 millimeters, preferably from 5 nanometers to 1 millimeter, more preferably from 10 nanometers to 100 micrometers. According to an embodiment, at least one of the nanogap electrodes is not tapered or pointed. In one embodiment, the active material comprises a plurality of nanoparticles, preferably a plurality of nano sheets.
In one embodiment, the active material comprises at least two pluralities of various nanoparticles. In one embodiment, the active material comprising a plurality of nanoparticles comprises semiconductor particles.
In one embodiment, the nanoparticles of the invention are inorganic.
In one embodiment, the nanoparticles of the invention are colloidal.
In one embodiment, the nanoparticles of the invention are crystalline. In one embodiment, the active material comprising a plurality of nanoparticles comprises oriented nanoparticles.
In one embodiment, the at least one active material does not comprise randomly arranged nanoparticles. In one embodiment, the at least one active material comprises randomly arranged nanoparticles. In one embodiment, the active material comprising a plurality of nanoparticles is located on the substrate.
In one embodiment, the active material comprising a plurality of nanoparticles or the film of nanoparticles covers partially or totally the substrate.
In one embodiment, the active material comprising a plurality of nanoparticles is located on the substrate and the first and second electrodes.
In one embodiment, the active material comprising a plurality of nanoparticles covers partially or completely the first and second electrodes.
In one embodiment, the active material comprising a plurality of nanoparticles is implemented into a film of nanoparticles. In one embodiment, the film of nanoparticles is obtained from colloidal nanoparticles. In one embodiment, the film of nanoplatelets is obtained from colloidal nanoplatelets.
In one embodiment, the active material comprising a plurality of nanoparticles is continuous from the first electrode to the second electrode. In one embodiment, said nanoparticles are used in the manufacture of a film of nanoparticles.
In one embodiment, said nanoparticles are used in the manufacture of a colloidal quantum dot film.
In one embodiment, said nanoparticles are used in the manufacture of a quantum dot solid.
In one embodiment, the active material comprising a plurality of nanoparticles has a thickness of the same order of magnitude as the absorption length of the plurality of nanoparticles.
In one embodiment, the active material comprising a plurality of nanoparticles has a thickness from 10 nanometers to 1 centimeter.
In one embodiment, the active material comprising a plurality of nanoparticles has a thickness from 10 nanometers to 10 micrometers.
In one embodiment, the active material comprising a plurality of nanoparticles has a thickness from 10 nanometers to 1 micrometer. In one embodiment, the active material comprising a plurality of nanoparticles has a thickness from 10 nanometers to 900 nanometers.
In one embodiment, the active material comprising a plurality of nanoparticles has a thickness from 10 nanometers to 800 nanometers.
In one embodiment, the active material comprising a plurality of nanoparticles has a thickness from 10 nanometers to 700 nanometers. In one embodiment, the active material comprising a plurality of nanoparticles has a thickness from 10 nanometers to 600 nanometers.
In one embodiment, the active material comprising a plurality of nanoparticles has a thickness from 10 nanometers to 500 nanometers. In one embodiment, the active material comprising a plurality of nanoparticles has a thickness from 10 nanometers to 400 nanometers.
In one embodiment, the active material comprising a plurality of nanoparticles has a thickness from 10 nanometers to 300 nanometers.
In one embodiment, the active material comprising a plurality of nanoparticles has a thickness from 10 nanometers to 200 nanometers.
In one embodiment, the active material comprising a plurality of nanoparticles has a thickness from 10 nanometers to 100 nanometers.
In one embodiment, the nanoparticles of the invention are 0D, ID, and 2D nanoparticles. One of the drawbacks of the 0D nanoparticle is their very sparse density of state only made of dirac comb which can typically include 2 electrons per state. On the other hand 2D systems are much more promising due to their larger density of state. They are consequently better candidate than the 0D system to sustain large density charging.
In one embodiment, the nanoparticles of the invention are for example nanocrystals, nanosheets, nanorods, nanoplatelets, nanoplates, nanoprisms, nanowalls, nanodisks, nanoparticles, nanowires, nanopowder, nanotubes, nanotetrapods, nanoribbons, nanobelts, nanowires, nanoneedles, nanocubes, nanoballs, nanocoils, nanocones, nanopillers, nanoflowers, quantum dots or combination thereof.
In one embodiment, the nanoparticles of the invention have the shape of a sphere, a cube, a tetrahedron, a rod, a wire, a platelet, a tube, a cube, a ribbon, or mixture thereof. It is one aim of the present invention to provide a large density of state and a large porosity. In one embodiment, the nanoparticles of the invention are nanosheets and the plurality of nanosheets presents an optimum porosity with efficient trade-off between the porosity and the charge density. In this embodiment, the plurality of nanosheets comprises pores size inferior to 1000 nm, or inferior to 100 nm, or inferior to 50 nm, or inferior to 10 nm, or inferior to 5 nm, or inferior to lnm, or inferior to 0.5 nm, or mixture thereof.
In one embodiment, the nanoparticles of the invention comprise a semi-conductor from group IV, group IIIA-VA, group IIA-VIA, group IIIA-VIA, group IA-IIIA-VIA, group IIA-VA, group IVA-VIA, group VIB-VIA, group VB-VIA, or group IVB-VIA.
In one embodiment, the nanoparticles of the invention comprise a material MxEy, wherein:
M is Zn, Cd, Hg, Cu, Ag, Al, Ga, In, Si, Ge, Pb, Sb, Sn, Pd, Fe, Au, Ti, Bi, W, Mo, V or a mixture thereof;
E is O, S, Se, Te, N, P, As or a mixture thereof; and
x and y are independently a decimal number from 0 to 5, at the condition that when x is 0, y is not 0 and inversely.
In one embodiment, the material MxEy comprises cationic elements M and anionic elements E in stoichiometric ratio, said stoichiometric ratio being characterized by values of x and y corresponding to absolute values of mean oxidation number of elements E and M respectively.
In one embodiment, the nanoparticles of the invention comprises a material MxNyEz, wherein:
M is selected from Zn, Cd, Hg, Cu, Ag, Al, Ga, In, Si, Sn, Ge, Pb, Sb, Sn, Pd, Fe, Au, Ti, Bi, W, Mo, V or a mixture thereof;
N is selected from Zn, Cd, Hg, Cu, Ag, Al, Ga, In, Si, Sn, Ge, Pb, Sb, Sn, Pd, Fe, Au, Ti, Bi, W, Mo, V or a mixture thereof;
E is selected from O, S, Se, Te, N, P, As or a mixture thereof; and x, y and z are independently a decimal number from 0 to 5, at the condition that when x is 0, y and z are not 0, when y is 0, x and z are not 0 and when z is 0, x and y are not 0.
According to one embodiment, the nanoparticles of the invention are made of a quaternary compound such as InAlGaAs, ZnAglnSe or GalnAsSb.
In one embodiment, the nanoparticles of the invention comprise a material from Si, Ge, Sn, CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, HgS, HgSe, HgTe, PbS, PbSe, PbTe, CuInS2, CuInSe2, AgInS2, AgInSe2, CuS, Cu2S, Ag2S, Ag2Se, Ag2Te, InN, InP, InAs, InSb, In2S3, Cd3P2, Zn3P2, Cd3As2, Zn3As2, ZnO, A1N, A1P, AlAs, AlSb, GaN, GaP, GaAs, GaSb, FeS2, Ti02, Bi2S3, Bi2Se3, Bi2Te3, MoS2, WS2, V02, and alloys and mixtures thereof.
In one embodiment, the nanoparticles of the invention present a heterostructure, which means that the nanoparticles of the invention are partially coated by at least one layer of inorganic material. In another embodiment, the nanoparticles of the invention present a core/shell structure, i.e. the nanoparticles comprise a core and a shell of semiconducting material.
In one embodiment, the nanoparticles of the invention have a core/shell structure, i.e. the core is totally coated by at least one layer of inorganic material.
In another embodiment, the nanoparticles of the invention comprises a core totally coated by a first layer of inorganic material, said first layer being partially or totally surrounded by at least one further layer of inorganic material.
In one embodiment, the core and the at least one layer of inorganic material are composed of the same material or are composed of different materials.
In one embodiment, the core and the at least one layer of inorganic material may be a semi-conductor from group IV, group IIIA-VA, group IIA-VIA, group IDA- VIA, group IA-IIIA-VIA, group IIA-VA, group IVA-VIA, group VIB-VIA, group VB-VIA, or group IVB-VIA. In another embodiment, the core and the at least one layer of inorganic material may comprise a material MxEy, wherein:
M is Zn, Cd, Hg, Cu, Ag, Al, Ga, In, Si, Ge, Pb, Sb, Sn, Pd, Fe, Au, Ti, Bi, W, Mo,
V or a mixture thereof;
E is O, S, Se, Te, N, P, As or a mixture thereof; and
x and y are independently a decimal number from 0 to 5, at the condition that when x is 0, y is not 0 and inversely.
In one embodiment, the core and the at least one layer of inorganic material comprise a material MxNyEz, wherein:
M is selected from Zn, Cd, Hg, Cu, Ag, Al, Ga, In, Si, Sn, Ge, Pb, Sb, Sn, Pd, Fe, Au, Ti, Bi, W, Mo, V or a mixture thereof;
N is selected from Zn, Cd, Hg, Cu, Ag, Al, Ga, In, Si, Sn, Ge, Pb, Sb, Sn, Pd, Fe, Au, Ti, Bi, W, Mo, V or a mixture thereof;
E is selected from O, S, Se, Te, N, P, As or a mixture thereof; and
x, y and z are independently a decimal number from 0 to 5, at the condition that when x is 0, y and z are not 0, when y is 0, x and z are not 0 and when z is 0, x and y are not 0.
In one embodiment the core and the at least one layer of inorganic material are made of a quaternary compound such as InAlGaAs, ZnAglnSe or GalnAsSb. In another embodiment, the core and the at least one layer of inorganic material may be composed of a material from Si, Ge, Sn, CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, HgS, HgSe, HgTe, PbS, PbSe, PbTe, CuInS2, CuInSe2, AgInS2, AgInSe2, CuS, Cu2S, Ag2S, Ag2Se, Ag2Te, InN, InP, InAs, InSb, In2S3, Cd3P2, Zn3P2, Cd3As2, Zn3As2, ZnO, A1N, A1P, AlAs, AlSb, GaN, GaP, GaAs, GaSb, FeS2, Ti02, Bi2S3, Bi2Se3, Bi2Te3, MoS2, WS2, V02, and alloys and mixtures thereof.
In one embodiment, the nanoparticles of the present invention comprise metallic materials such as gold, silver, copper, aluminum, iron, platinum, lead, or palladium.
In another embodiment, the nanoparticles of the present invention present a hetero structure comprising metallic materials and semiconductor materials. In an embodiment of the invention, the nanoparticle of the invention may be further surrounded by a "coat" of an organic capping agent. The organic capping agent may be any materials, but has an affinity for the semiconductor surface. In general, the capping agent can be an isolated organic molecule, a polymer (or a monomer for a polymerization reaction).
In one embodiment, organic capping agents are selected from trioctylphosphine oxide, organic thiols, amines, phosphines, carboxylic acids, phosphonic acids, sulfonic acids, trialkoxysilanes, alkyl and aryl halides; and mixtures thereof.
In another embodiment of the invention, the nanoparticle of the invention may be further surrounded by a "coat" of an inorganic capping agent. In one embodiment, the inorganic capping agent comprises an inorganic complex, an extended crystalline structure, metals selected from transition metals, lanthanides, actinides, main group metals, metalloids and mixture thereof.
In one embodiment, the inorganic capping agent comprises ionic salts. In another embodiment, the nanoparticles of the invention may be surrounded by a mixture of inorganic and organic capping agent.
Preferably, the nanoparticles of the invention for use in a transistor, a phototransistor or photodetector are selected in the group comprising: CdSe, CdTe, CdS, HgTe, PbS, PbSe, PbTe and the core/shell structures such as CdSe/CdS, CdSe/CdZnS, CdTe/CdS/CdZnS, CdS/ZnS, PbS/CdS, PbSe/CdS.
In one embodiment, the active material of the photodetector of the present invention comprises inorganic semiconductors, preferably crystalline inorganic semiconductors.
In a preferred embodiment, the active material of the photodetector of the present invention comprises core inorganic semiconductor or type I heterostructures. In a preferred embodiment, the active material of the photodetector of the present invention comprises CdSe, CdS, CdTe, ZnS, ZnSe, PbS, PbSe, PbTe, HgS, HgSe, HgTe, InP, InAs, GaAs, and mixture thereof. In a preferred embodiment, the active material of the photodetector of the present invention does not comprise amorphous nanoparticles, or type II heterostructures.
Even if type II heterostructures may have looked appealing since they tend to help dissociate the electron hole pair at the nanoparticle level even in absence of electric field, once processed under the form of a film, the p part will behave as electron traps and the n part as hole traps, which is not desirable. An example of these type II heterostructures is core-shell structure made of CdSe and CdTe.
In one embodiment, the nanoparticles are not selected from PbS.
In one embodiment, the nanoparticles are not selected from carbon-based nanoparticles such as carbon nanowires, carbon nanotubes (multi-walled or single- walled), graphene or combination thereof.
In one embodiment, the nanoparticles are not selected from silicon nanoparticles such as silicon quantum dots or silicon nanowires.
In one embodiment, the nanoparticles are not selected from silver nanowire mesh. In one embodiment, the nanoparticles are not selected from metal oxide such as titanium dioxide.
In one embodiment, the nanoparticles are not selected from materials that can undergo an intercalation/de-intercalation reaction with lithium ions.
In one embodiment, the nanoparticles are not selected from perovskite nanoparticles. In one embodiment, the nanoparticles of the present invention have at least one dimension having a size of about 0.3 nm to less than 1 μιη, about 0.5 nm to about 700 nm, about 1 nm to about 500 nm, about 1.5 nm to about 200 nm, about 2 nm to about 100 nm.
In one embodiment, the nanosheets of the present invention have a thickness of about 0.3 nm to about 10 mm, about 0.3 nm to about 1 mm, about 0.3 nm to about 100 μιη nm, about 0.3 nm to about 10 μιη, about 0.3 nm to about 1 μιη, about 0.3 nm to about 500 nm, about 0.3 nm to about 250 nm, about 0.3 nm to about 100 nm, about 0.3 nm to about 50 nm, about 0.3 nm to about 25 nm, about 0.3 nm to about 20 nm, about 0.3 nm to about 150 nm, about 0.3 nm to about 10 nm, about 0.3 nm to about 5 nm.
In one embodiment, the nanosheets of the present invention have a lateral dimensions (length and/or width) of at least 1.5 times its thickness.
In another embodiment of the invention, the lateral dimensions of the nanosheet are at least 2, 2.5, 3, 3.5, 4.5, 5 times larger than the thickness.
In one embodiment, the lateral dimensions of the nanosheet are from at least 0.45 nm to at least 50 mm. In one embodiment, the lateral dimensions of the nanosheet are from at least 2 nm to less than 1 m, from 2 nm to 100 mm, from 2 nm to 10 mm, from 2 nm to 1 mm, from 2 nm to 100 μηηι, from 2 nm to 10 μηηι, from 2 nm to 1 μηηι, from 2 nm to 100 nm, from 2 nm to 10 nm.
In one embodiment, the nanosheets of the invention has a quasi-2D structure. In one embodiment, the nanoparticles are coupled to a high mobility material.
In one embodiment, the nanoparticles is mixed or blended with a high mobility material.
In one embodiment wherein at least two electrodes are spaced by a nanogap, the plurality of nanoparticles forming the active material are bridging said at least two electrodes; and at least 2% of their projected areas are overlapping with the at least two electrodes (i.e. each of the nanoparticles of the plurality of nanoparticles has an overlap area with the at least two electrodes spaced by a nanogap higher than 2% of the area of each of said nanoparticles).
In one embodiment, the plurality of nanoparticles bridging the at least two electrodes spaced by a nanogap have at least 5%, 10% or preferably 20%, of their projected surface overlapping with the at least two electrodes spaced by a nanogap. In one embodiment, the plurality of nanoparticles bridging the at least two electrodes spaced by a nanogap have at least 1% of their projected area overlapping with each of the at least two electrodes spaced by a nanogap (i.e. each of the nanoparticles of the at least one nanoparticle has an overlap area with each of the at least two electrodes spaced by a nanogap higher than 1% of the area of each of said nanoparticles). In one embodiment the plurality of nanoparticles bridging the at least two electrodes spaced by a nanogap have at least 2.5%, 5% or preferably 10% of their projected surface overlapping with each of the at least two electrodes spaced by a nanogap.
In one embodiment, the film of nanoparticles forming the active material and bridging the at least two electrodes spaced by a nanogap has at least 2% of its projected area overlapping with the at least two electrodes spaced by a nanogap (i.e. the film of nanoparticles has an overlap area with the at least two electrodes spaced by a nanogap higher than 2% of the area of said film). According to an embodiment the film of nanoparticles bridging the at least two electrodes spaced by a nanogap has at least 5%, 10% or preferably 20% of its projected surface overlapping with the at least two electrodes spaced by a nanogap.
According to an embodiment, the film of nanoparticles forming the active material and bridging the at least two electrodes spaced by a nanogap has at least 1% of its projected area overlapping with each of the at least two electrodes spaced by a nanogap (i.e. the film of nanoparticles has an overlap area with each of the at least two electrodes spaced by a nanogap higher than 1% of the area of said film). According to an embodiment the film of nanoparticles bridging the at least two electrodes spaced by a nanogap has at least 2.5%, 5% or preferably 10% of its projected surface overlapping with each of the at least two electrodes spaced by a nanogap. In one embodiment, the electrolyte has at least one common interface with at least part of the active material comprising a plurality of nanoparticles.
In one embodiment, the electrolyte has only one common interface with at least part of the active material comprising a plurality of nanoparticles. In one embodiment, the matrix of the electrolyte is not mixed with at least part of the active material comprising a plurality of nanoparticles.
In one embodiment, the matrix of the electrolyte is not mixed with the active material comprising a plurality of nanoparticles.
In one embodiment, the matrix of the electrolyte is not mixed with the film of nanoparticles.
In one embodiment, the matrix of the electrolyte remains outside of the active material.
In one embodiment, the active material is not saturated by the electrolyte.
In one embodiment, the electrolyte has a thickness from 10 nanometers to 1 centimeter, preferably from 500 nanometers to 2 millimeters, more preferably from 1 micrometer to 10 micrometers.
In one embodiment, solid, polymer, gel, ion-gel or liquid electrolytes may be implemented, preferably a gel or solid electrolyte.
In one embodiment, contact between the electrolyte and the first and second electrodes is prevented by the active material comprising a plurality of nanoparticles.
In an embodiment, the at least one electrolyte can be in the form of an aqueous solution of a dissolved ionic chemical compound (or compounds), a non-aqueous solution of a dissolved ionic chemical compound (or compounds), a polymer electrolyte, a gel electrolyte, a solid electrolyte or a molten salt electrolyte.
In one embodiment, the electrolyte comprises a matrix and ions.
In one embodiment, the electrolyte comprises a polymer matrix.
In one embodiment, the polymer matrix of the electrolyte comprises polystyrene, poly(N-isopropyl acrylamide), polyethylene glycol, polyethylene, polybutadiene, polyisoprene, polyethylene oxide, polyethyleneimine, polymethylmethacrylate, polyethylacrylate, polyvinylpyrrolidone, polypropylene glycol, polydimethylsiloxane, polyisobutylene, or a blend/multiblocks polymer thereof.
In one embodiment, the electrolyte comprises ions salts.
In one embodiment, the polymer matrix is doped with ions salts. In one embodiment, the ions salts is LiCl, LiBr, Lil, LiSCN, LiC104, KC104, NaC104, ZnCl3 ~, ZnCl4 2", ZnBr2, LiCF3S03, LiPF6, LiAsF6, LiN(S02CF3)2, LiC(S02CF3)2, LiBF4, NaBPh4, NaCl, Nal, NaBr, NaSCN, KC1„ KBr, KI, KSCN, LIN(CF3S02)2, or mixture thereof.
In one embodiment, the electrolyte comprises material that contains mobile ions of lithium, sodium, potassium, ammonium, hydrogen, copper, silver or mixture thereof.
In one embodiment, the electrolyte comprises polymers and glasses, including but not limited to PEG, PEO, PVDF, PET, PTFE, FEP, FPA, PVC, polyurethane, polyester, polyglycol, silicone, some epoxies, polypropylene, polyimide, polycarbonate, polyphenylene oxide, polysulfone, calcium magnesium aluminosilicate glasses, E-glass, alumino-borosilicate glass, D-glass, borosilicate glass, silicon dioxide, quartz, fused quartz, silicon nitride, silicon oxynitride, or mixture thereof.
In one embodiment, the electrolyte comprises ionic liquid.
In one embodiment, the polymer matrix and the ions are replaced by a polymerizable ionic liquid. In one embodiment, the electrolyte is transparent in a wavelength window compatible with the absorption spectrum of the plurality of nanoparticles. Compatible means herein that the substrate is at least partly transparent in the range of wavelength wherein the plurality of nanoparticles is absorbing. Partly transparent means herein that the substrate has a transmittance of at least 50%, preferably at least 75%, more preferably at least 90%. In one embodiment, the electrolyte is transparent in the visible, i.e. in a wavelength range from about 380 nanometers to about 750 nanometers.
In one embodiment, the electrolyte is transparent in the ultraviolet range of wavelength, i.e. in a wavelength range from about 10 nanometers to about 380 nanometers. In one embodiment, the electrolyte is transparent in the infrared range of wavelength, i.e. in the wavelength range from about 750 nanometers to about 1 000 000 nanometers, preferably from about 750 nanometers to about 50 000 nanometers, more preferably from about 750 nanometers to about 3000 nanometers.
According to one embodiment, the substrate is partly transparent in the visible and/or in the ultraviolet range of wavelength and/or in the infrared range of wavelength.
In one embodiment, the electrolyte transparency window is at least lnm large, preferably at least lOnm large and more preferably above 50nm large.
In one embodiment, the electrolyte is transparent in two wavelength windows compatible with the absorption spectrum of the plurality of nanoparticles. In one embodiment, the electrolyte transparency window is made of several windows in order to fit the absorption spectrum of the multicolor detector, preferably of several narrow transparency windows i.e. of at most 50 nm large.
In one embodiment, the nanoparticle surface chemistry is chosen to be a counterion of one of the ions of the electrolyte. In one embodiment, the nanoparticle surface chemistry is chosen so that the nanoparticles and the electrolyte can form a redox reaction.
In one embodiment, at least one ion from the electrolyte can reversibly give one or more electron(s) to the active material as in redox based reactions.
Examples of pairs of nanoparticle surface chemistry/ion include but is not limited to: OH7Li+, OH7Na+, OH7K+, OH 7NH4 +, OH /any ammonium ion, OH /any ionic liquid, 027Li+, O 27Na+, O 27K+, O 27NH4 +, O 27any ammonium ion, O 27any ionic liquid, HS" /Li+, HS 7Na+, HS 7K+, HS 7NH4 +, HS /any ammonium ion, HS /any ionic liquid, SCN /Li+, SCN7Na+, SCN7K+, SCN7NH4 +, SCN7any ammonium ion, SCN7any ionic liquid, NH27Li+, NH27Na+, NH27K+, NH27NH4 +, NH27any ammonium ion, NH27any ionic liquid, S27Li+, S27Na+, S27K+, S27NH4 +, S27any ammonium ion, S27any ionic liquid, Se27Li+, Se27Na+, Se27K+, Se27NH4 +, Se27any ammonium ion, Se2 /any ionic liquid, Te27Li+, Te27Na+, Te27K+, Te27NH4 +, Te27any ammonium ion, Te27any ionic liquid, C17Li+, C17Na+, C17K+, C17NH4 +, C17any ammonium ion, C17any ionic liquid, Br7Li+, Br 7Na+, Br 7K+, Br 7NH4 +, Br /any ammonium ion, Br /any ionic liquid, I7Li+, 17Na+, I 7K+, I 7NH4 +, I 7any ammonium ion, I /any ionic liquid, Any metal-chalcogenide/ Li+, Any metal-chalcogenide /Na+, Any metal-chalcogenide /K+, Any metal-chalcogenide /NH4 +, Any metal-chalcogenide /any ammonium ion, Any metal-chalcogenide /any ionic liquid, Cd2+/Cl", Cd2+/Br", Cd2+/r, Cd2+/S042", Cd2+/C104 ", Cd2+/BF4 ", Cd2+/N03 ~, Cd2+/ any ionic liquid, Pb2+/Cl", Pb2+/Br", Pb2+/T, Pb2+/S042", Pb2+/C104 ", Pb2+/BF4 ", Pb2+/N03 ", Pb2+/ any ionic liquid, Zn2+/Cl", Zn2+/Br", Zn2+/I", Zn2+/S042", Zn2+/C104 ", Zn2+/BF4 ", Zn2+/N03 ", Zn2+/ any ionic liquid, Hg2+/Cl", Hg 2+/Br", Hg 2+/I", Hg 2+/S042", Hg 2+/C104 ", Hg 2+/BF4 ", Hg2+/N03 ", Hg2+/ any ionic liquid, NH3 +/C1", NH +/Br", NH3 +/I", NH3 +/S042", NH3 +/C104 ", NH3 +/BF4 ", NH3 +/N03 ", NH3 +/ any ionic liquid.
In one embodiment, the gate capacitance per unit of surface of active material is higher than that expected to be formed at the electrolyte channel interface of standard ionic double layer: c L = r 0 ; wherein £ is the vacuum permittivity, £ is the electrolyte aDL
dielectric constant and aDL is the width of the double layer formed at the electrolyte- active material interface.
This invention relates to a photodetector having an ultra large capacitance. In one embodiment, the electronic component, preferably the photodetector, has a gate
5 -2 -2 capacitance from 1 to 10 μΡ ι " , preferably from 10 to 15 000 μΡ ι " , more
-2 -2 preferably from 20 to 1100 μΡ ι " , even more preferably from 20 to 500 μΡ ι " . In another embodiment, the electronic component, preferably the photodetector, has a gate capacitance superior to 30 μΡχι -'2 , from 30 to 105 μΡχι -'2 , preferably from 30 to
15 000 μΡχι -'2 , more preferably from 30 to 1100 μΡχι -'2 , even more preferably from 30 to 500 μΕαη 2. In another embodiment, the electronic component, preferably the photodetector, has a gate capacitance of at least 30 μΡχι -'2 , preferably at least 100 μΡχι -'2 , 200 μΡχι -'2 , 300 μΕαϊϊ"2, 400 μΡχηι 2, 500 μΡ.αη 2, 1000 μΕαιϊ"2, 1500 μΕαη 2, 5000 μΕαη 2, 10000 μΕαιϊ"2, 15000 μΕαη 2.
In one embodiment, the electronic component, preferably the photodetector, of the present invention presents good cycling properties above 100 cycles.
In one embodiment, the electronic component, preferably the photodetector, presents on/off ratio from 1 to 1011.
In one embodiment, the electronic component, preferably the photodetector, presents at room temperature subthreshold slope from 20mV/decade to 3V/decade, preferably from 50mV/decade to lV/decade, more preferably from 59 mV/decade to 600 mV/decade.
In one embodiment, the photodetector presents a responsivity ranging from ΙμΑ. Υ'1 to 1MA.W"1, preferably from ΙμΑ. Υ"1 to lkA.W-1, more preferably from ImA.W"1 to lkA.W-1.
In one embodiment, the photodetector presents a detectvity ranging from 10 cm. Hz1/2W_1 (also named "Jones") to 1014 jones and more preferably from 108 jones to 10 13 jones.
In one embodiment, ions from the electrolyte migrate at the interface between the electrolyte and the active material comprising a plurality of nanoparticles.
In one embodiment, the ions from the electrolyte migrate within the active material comprising a plurality of nanoparticles. In on embodiment, bulk doping or bulk charging is achieved within the active material comprising a plurality of nanoparticles.
In on embodiment, bulk doping or bulk charging is achieved within the film of nanoparticles. In one embodiment, charges are injected in the active material comprising a plurality of nanoparticles; the introduction of the ions induces indeed a charging of the quantum states of the nanoparticles.
In one embodiment, the continuity of the active material comprising a plurality of nanoparticles prevents direct contact between the electrolyte and the first and second electrodes therefore preventing leakage through the dielectric.
It should be understood that the spatial descriptions (e.g., "above", "below", "up", "down", "top", "bottom", etc.) made herein are for purposes of illustration only, and that devices of the present invention can be spatially arranged in any orientation or manner. In one embodiment, the manufacturing process for preparing the electronic component, preferably the photodetector, of the present invention comprises three main steps:
Electrodes fabrication and deposition onto a substrate,
Deposition of the nanoparticles and nanoparticle's ligand exchange after or before deposition,
- Electrolyte deposition.
More precisely, the method for producing an electronic component, preferably a photodetector, comprises:
a) the deposition of the first and the second electrodes onto a substrate,
b) the preparation of a solution of nanoparticles,
b') the nanoparticle's ligand exchange step in solution,
c) the deposition of the previous solution of nanoparticles, which will form the active material onto the electrodes and substrate, c') if step b') is not implemented, nanop article's ligand exchange step on the active material comprising a plurality of nanoparticles,
d) the electrolyte deposition on the active material comprising a plurality of nanoparticles,
e) the third electrode deposition on the electrolyte.
In one embodiment, the at least first and second electrodes are fabricated using a lift-off procedure onto the substrate.
In one embodiment, the source electrode and the drain electrodes may be deposited using conventional deposition techniques, including for example, drop casting, inkjet printing, screen printing, gravure printing, flexographic printing or any other means that a person skilled in the art would find appropriate.
In one embodiment, thin metallic electrodes having a thickness from 1 to 40 nanometers, preferably from 10 to 30 nanometers are used.
In one embodiment, metallic electrodes having a thickness from 1 to 1000 nanometers, preferably from 10 to 100 nanometers, more preferably from 20 to 75 nanometers are used.
In one embodiment, the nanoparticles of the invention are dispersed in a solvent, such as for example a mixture of hexane and octane with a volume ratio of 9: 1, in order to obtain the solution of nanoparticles. In one embodiment, the solution of nanoparticles of step b) is deposited during step c) onto the substrate.
In one embodiment, the solution of nanoparticles of step b) is deposited during step c) onto the electrically insulating substrate and the first and second electrodes.
In one embodiment, the solution of nanoparticles deposited during step c) comprises various nanoparticles. In another embodiment, the steps b), b'), c), c') may implemented more than once with various nanoparticles. According to one embodiment, the electrodes are processed with a gas treatment before step c).
According to one embodiment, the electrodes are treated with molecules such as short- chain alkane thiols to improve the adhesion of the nanoparticles before step c). According to one embodiment, the electrodes are treated with a coating for passivating the surface of the at least two electrodes before step c).
According to an embodiment, the electrodes are annealed before step c) at a temperature ranging from 100°C to 1000°C.
In one embodiment, the deposition of nanoparticles is achieved during step c) by sputtering techniques, evaporation techniques, electrophoretic deposition, vacuum methods, lithography process, spray pyrolysis, hot and cold plasma, inert gas phase condensation techniques or any other means that a person skilled in the art would find suitable.
In one embodiment, the deposition of nanoparticles is achieved during step c) by drop casting, spin coating, dip coating, spray coating, screen printing, inkjet printing or any other means that a person skilled in the art would find appropriate.
In one embodiment, the nanoparticles prepared in solution at step c) present wide or narrow band gap.
In an embodiment, for narrow band gap material, nanoparticle's ligand exchange is performed in the active material comprising a plurality of nanoparticles after deposition or on the nanoparticles in solution prior to the deposition, preferably in the active material comprising a plurality of nanoparticles after deposition.
In an embodiment, for wide band gap material nanoparticle's ligand exchange is performed in the active material comprising a plurality of nanoparticles after deposition or on the nanoparticles in solution prior to the deposition, preferably on the nanoparticles in solution prior to the deposition. In one embodiment, nanoparticle's ligand exchange is performed on the active material comprising a plurality of nanoparticles during step c'), for example by dipping the nanoparticles in a solution.
In one embodiment, the nanoparticle's ligand exchange is performed directly in solution prior to the deposition of nanoparticles as in step b').
In one embodiment, nanoparticle's ligand exchange improves the conduction properties of the active material.
In one embodiment, the electronic component, preferably the photodetector, in progress is annealed before step d) at low temperature, typically below 400°C, or below 300°C or below 200°C, or below 100°C.
In one embodiment, during step d) the electrolyte is brushed on the active material comprising a plurality of nanoparticles.
In one embodiment, the electrolyte is deposited using any printing methods that a person skilled in the art would find suitable, such as for example spin coating or dip coating, or drop casting.
In one embodiment, the electrolyte is prepared by dissolving an ion salt and a polymer matrix in a polar solvent. In one embodiment, the electrolyte is prepared by melting ion salt in the polymer matrix at moderate temperature, typically 150°C.
In one embodiment, the gate electrode deposited on the electrolyte during step e) is a metallic contact deposited by any methods that a person skilled in the art would find suitable such as for example drop casting or metal evaporation techniques.
Due to their properties as mentioned here above, the electronic components of the invention are particularly useful as transistor, photodetector or phototransistor. The term phototransistor is used herein to describe a transistor device used as light detector. In one embodiment, the photodetector of the invention is a phototransistor. In one embodiment, the source electrode and the drain electrode are connected to opposite terminals of a common voltage source.
In another embodiment, the gate electrode is connected to a second voltage source.
In one embodiment, the transistor, the phototransistor and/or the photodetector are used as part of a global product. In this embodiment, the global product may comprise more than one transistor, phototransistor and/or photodetector.
In one embodiment, the transistor of the present invention comprises at least three electrodes: a source electrode, a drain electrode and a gain electrode.
In one embodiment, the transistor is an electrochemical transistor.
In one embodiment, the transistor of the present invention comprises one drain electrode, one source electrode and two gate electrodes. In this embodiment, the charge density through the fourth gate can be modulated quickly.
In one embodiment, the photodetector and/or the phototransistor device of the invention comprises at least 2, 3, 4 or 5 electrodes.
In one embodiment, the phototransistor and/or photodetector comprises more than one active material. These active materials can be stacked or not.
In one embodiment, the phototransistor and/or photodetector comprises two active materials, one p type and on n type. Each material can be independently addressed using the gate voltage as a switch. The system can be used as a bicolor detector.
In one embodiment, the phototransistor and/or photodetector comprises at least two active materials, with different band gap. Each material can be addressed by tuning the gate voltage. The system can be used as a multicolor detector.
In one embodiment, the active material used to build the phototransistor and/or photodetector is processed under a pixel form. In one embodiment, the active material used to build the phototransistor and/or photodetector is processed under an array of pixel.
In one embodiment the gate electrodes is grounded and a source and drain bias with different sign is applied.
In one embodiment the gate electrodes is grounded and a pn junction is formed between the drain and source.
In one embodiment, a pn junction is formed between two of the electrodes and this photodetector is used as a LED or as a photodetector operating in photovoltaic mode.
Thus the present invention also relates to an array comprising a plurality (i.e. at least two) of photodetectors and/or phototransistors of the present invention.
In one embodiment, the array comprises a plurality of photodetectors or phototransistors and a readout circuit electrically connected to the plurality of photodetectors or phototransistors. In one embodiment wherein at least two photodetectors or phototransistors are implemented, a single read out circuit is needed (i.e. the at least two active materials are addressed using the same drain source bias). In one embodiment each photodetectors or phototransistors comprises a read-out circuit.
In one embodiment, the active material used to build the phototransistor and/or photodetector is coupled to a readout circuit.
The present invention also relates to an imaging chips called focal plane array comprising the array of the present invention and optionally the readout circuit. The focal plane array may be used in an imaging device.
In one embodiment, at least one phototransistor and/or photodetector of the present invention is integrated into an imaging device such as a camera.
In one embodiment, the invention can find applications in digital and analog switches, signal amplifiers, power regulators, equipment controllers and as building blocks of integrated circuits. In one embodiment, the invention can find applications in imaging sensors, remote sensing, night vision and ultra-low power detection.
BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 illustrates the three different regimes of operation of the electronic component: a) on left the ion injection regime (low frequency regime), b) on middle the double electrostatic layer (intermediate frequency regime) and c) on right the high frequency mode where the electrolyte is used as a dielectric.
Figure 2 is a sectional view of an electronic component according to one embodiment of the present invention.
Figure 3 shows a sectional view of a detector structure according to one embodiment of the present invention.
Figure 4 shows a sectional view of an electronic component structure in one embodiment of the present invention, in a planar geometry. Figure 5 shows a sectional view of an electronic component structure in one embodiment of the present invention, in a vertical geometry.
Figure 6 shows the typical charging curve for an electronic component of the present invention. It shows the drain source current as a function of gate bias for CdSe/CdS core/shell nanoplatelets (VDS=0.5V). Figure 7 shows a curve comparing an electronic component of the present invention with the usual fabrication method. It shows drain source current as a function of the gate bias for a film of HgTe nanoparticles. Data for the film charged through the electrolyte (LiC104 in PEG 88k) and via a back gating through the Si02 layer of the substrate were plotted on the same graph. Figure 8 illustrates the variation of the optical spectra of a film of PbS colloidal quantum dots at different charging time. Figure 9 illustrates the cycling properties of an electronic component of the present invention. It shows drain source current as a function of the time while the gate bias is cycled for a film of CdSe/CdS nanoplatelets (electrolyte is LiC104 in PEG 6k). At each cycle a gate step crenel is applied from 0 to 2V. The drain source bias is lOmV. Figure 10 illustrates the responsivity of a phototransistor made of CdSe-CdS core shell nanoplatelets as a function of gate bias.
Figure 11 illustrates a scheme of bicolor phototransistor using two pluralities of nanoparticles.
Figure 12 illustrates a scheme of phototransistor according to one embodiment of the present invention comprising a substrate, three electrodes: a source electrode (S), a drain electrode (D) and a gate electrode (G), a plurality of nanoparticles and an electrolyte (E).
EXAMPLES The present invention is further illustrated by the following examples.
1. Nanoparticles synthesis PbS spherical quantum dots ( QD )
In a three-neck flask, we introduce 0.9g lead oxide and 40mL of oleic acid. The mixture is degased for lh at 100°C under vacuum and then heated under Argon at 150°C for three hours. In the glove box 0.4mL of Bis(trimethylsilyl)sulfide (TMSS) are mixed in 20mL of octadecene (ODE). In a lOOmL three-neck flask, 12ml of the lead oleate (PbOA) mixture previously prepared are quickly degased at 100°C and then heated at 150°C under Argon. 6mL of the solution of TMSS in ODE are quickly injected to the flask and the reaction performed for 3 minutes. Finally the solution is quickly cooled to room temperature. The solution is precipitated by adding ethanol and centrifuged for 5min at 3000rpm. The solid is redispersed in toluene. The cleaning step is repeated a second time. At the third cleaning, selective precipitation is performed to separate the different size.
QD with a bluer band gap have also been. In this case 0.45g of lead oxide is stirred in 5ml of oleic acid overnight at 100°C under vacuum. The obtained yellowish solution is dissolved by adding 15ml of ODE. The flask is then switch under Argon and the temperature risen up to 125°C. Then 10ml of a TMMS in ODE solution (0.1M) are quickly injected. The heating mantle is removed and the solution gently cooled down up to room temperature. The three steps cleaning procedure including selective precipitation is done using a mixture of methanol/ethanol as polar solvent and chloroform as non-polar solvent.
^ PbS nanocube
0.44g of lead oxide is mixed in a three-neck flask with 2mL of oleic acid and lOmL of phenyl ether at 150°C under Argon for thirty minutes. In the meanwhile 32mg of sulfur flake are sonicated with 2mL of filtered oleylamine. The obtained mixture is red- orange. The flask is heated up to 190°C and the sulfur in oleylamine quickly injected. The reaction is then conducted at 180°C for 5 minutes. The cleaning process is done three times by adding ethanol/methanol as non-solvent and toluene as non-polar solvent. PbSe sphericalQD
In the glove box a 1M solution of trioctylphosphine selenide (TOPSe) is prepared by stirring Se powder in trioctylphosphine (TOP) at room temperature. In a three-neck flask 650mg of trihydrate lead(II) acetate Pb(Oac)2(H20)3 are introduced with 2mL of phenyl ether, 1.5mL of oleic acid and 8mL of TOP. The solution is degased, as well as a second flask only filled with lOmL of pure phenyl ether, for lhour at 85°C. The one containing the lead precursor is cooled to 45°C and 1.7mL of the TOPSe solution is added. The solution is kept under stirring condition for 5 extra minutes. Finally the content of the flask is introduced in a 20mL syringe. The flask filled with just phenyl ether is heated up to 200°C under Argon. The content of the syringe is quickly injected. The Temperature of the flask cooled down to 140°C after the injection. During the next 90s the temperature is set at 120°C to avoid a too fast cooling. After this delay the flask is promptly cooled to room temperature. The cleaning is operated in the first step by addition of methanol and ethanol. After centrifugation the solid is dispersed in toluene. For the second (third) cleaning step ethanol (acetone/ethanol) is used.
> HgTe QD In the glove box a 1M solution of trioctylphosphine telluride (TOPTe) is prepared by a slow stirring of Te powder in trioctylphosphine (TOP). In a three neck flask 135mg of HgCl2 and 7.4g of octadecylamine are degased under vacuum for lhour at 120°C. The atmosphere is then switch to Argon and the solution heated at 80°C. 0,5ml of the 1M TOPTe are quickly injected and the reaction is performed at the same temperature for 5min. The solution is quenched by a quick addition of dodecanthiol. Finally the flask is cooled down to room temperature. The obtained dark solution is then splitted between two centrifuge tubes filled with a 10% in volume mixture of dodecathiol (DDT) in tetrachloroethylene (TCE) and a droplet of TOP. The solution is precipitated by addition of methanol. After centrifugation the solid is dried and redispersed in chloroform. The cleaning step is repeated three times. CdS rods
In the glove box, 0.18g of sulfur powder are stirred in 20ml of TOP up to dissolution and formation of trioctylphosphine sulfide (TOPS). The final solution is reddish. In a 100ml three-neck flask, 0.23g of CdO, 0.83g of n-tetradecylphosphonic acid (nTDPA) and 7g of trioctylphosphine oxyde (TOPO) are degased under vacuum for two hours at 80°C. Then the flask is switch under Argon and the temperature risen up to 340°C. Above 300°C the solution turns colorless. After 5min the flask is cooled to 300°C, every two minutes 0.4ml of the TOPS mixture is injected. The color of the solution turn yellowish after 30minutes and this color will increase up to the end. Once all the TOPS have been injected the heating mantle is removed and the flask quickly cooled down. Around 70°C some toluene is added to avoid the TOPO solidification. The cleaning process is repeating three times by precipitating the rods by adding ethanol and redispersing them in toluene. > CdSe QD
In a three-neck flask, 8ml of ODE, 1.5g of TOPO and 0.75ml of Cd(OA)2 at 0.5M in oleic acid are degased for 30minutes under vacuum. Then under argon flow, the temperature is set at 280°C and a mixture of 3ml of oleylamine and 4ml of TOPSe at 1M in TOP are quickly injected at 300°C while the temperature is set at 280°C. After 8 minutes, the reaction is stopped and the quantum dots are precipitated twice with ethanol and resuspended in hexane. CdSe nanoplatelets
In a first step Cadmium myristate (Cd(Myr)2) is prepared. In a typical synthesis 240mg of Cd(Myr)2, 25mg Se powder are mixed in 30ml of ODE, the solution degased under vacuum for 20min at room temperature. Then the atmosphere is switch to Argon and the temperature is set to 240°C. At 204°C 40mg of Cd(OAc)2 are quickly added. The reaction is performed 12min at 240°C. 1ml of oleic acid is quickly injected to quench the reaction and the solution is cooled down. The precipitation of the nanoplatelets is done by adding ethanol. After centrifugation the obtained solid is redispersed in hexane. The cleaning procedure is repeated three times. CdSe/CdS core/shell nanoplatelets
Two procedures can be performed to obtain a CdS shell on CdSe core.
In a first procedure, 30mg of NaSH are mixed in 4 ml of N methyl formamide (NMFA) in a 20mL vial up to dissolution. Then 500μΕ of the CdSe core in solution in hexane are added in the vial. The solution is stirred until a complete transfer of the nanoparticles in the NMFA phase. Then 500μ1 of 0.2M cadmium acetate in NMFA are added in the vial. The reaction is performed for lhour at room temperature under stirring. Precipitation is ensured by addition of ethanol. After centrifugation the obtained solid is dispersed in NMFA. The cleaning step is repeated a second time.
As an alternative procedure to grow the shell it is possible to dissolve 30mg of Na2S are mixed in 2 ml of NMFA in a 4mL vial up to dissolution. The core are then precipitated by addition of acetonitrile to remove the excess of sulfide and redispersed in NMFA. Then 500μ1 of 0.2M cadmium acetate in NMFA are added in the vial. After the almost immediate reaction the excess of precursors is removed by precipitation of the nanocrystals with a mixture of toluene and acetonitrile (5: 1). The solid obtained by centrifugation is redisolved in NMFA. The procedure is repeated 3.5 times. The final nanoparticles are stored in NMFA. CdTe nanoplatelets
In a first step Cadmium propanoate (Cd(Prop)2) is prepared by mixing 1.036g of CdO in 10ml of propionic acid under Argon for 1 hour. Then the flask is open to air and the temperature risen to 140°C up to the point the volume get divided by a factor two. The whitish solution is precipitated by addition of acetone. After centrifugation the solid is dried under vacuum for 24 hours.
In the glove box 1M TOPTe is prepared by stirring 2.55g of Te pellets in 20ml of TOP for four days at room temperature.
In a three-neck flask 0.13g of Cd(Prop)2, 160μιη of oleic acid and 10ml ODE are degased for 90 minutes at 95°C. Then the atmosphere is switched to Argon and the temperature risen to 210°C. 0.2mL of 1M TOPTe is quickly injected in the flask. After 20 minutes the reaction is quenched by adding lmL of oleic acid and cooling down the flask at room temperature. The cleaning process is done by adding Ethanol to precipitate the CdTe nanoplatelets. The solid obtained after centrifugation is redispersed in hexane. This procedure is repeated three times.
2. Ion- el electrolyte preparation
The electrolyte is a mixture of polyethylene glycol (PEG) or polyethylene oxide (PEO) with a given molar weight and ions. The molar ratio between the cation and the oxygen is taken equal to 16. For a typical electrolyte 50mg of L1CIO4 and 230mg of PEG (MW=6000g.mol-l) are heated together at 150°C on a hot plate in the glove box. For higher PEG/PEO molar weight the mixture is heated at 200°C. Processing the electrolyte in air has not lead to any noticeable change. The electrolyte may also be prepared in an alternative way. The goal of this change is to initially have a liquid electrolyte which can be deposited in a thinner film compared to what can be achieved with solventless preparation. In this approach 250mg of L1CIO4, 1.15g of PEG 88k and 3g of acetonitrile are stirred in a 20mL vial, up to obtain a clear solution.
3. Electrodes preparation
Electrodes are fabricated using a regular lift-off procedure onto a Si/Si02 wafer with an oxide thickness of 500nm. A thermal evaporation of Cr (2.5nm) and gold (17.5nm) is used for the contact. Electrodes are composed of 25 interdigitated pairs which are 2.5mm long. Two sets of electrodes have been designed with a spacing of 10 and 20μιη. The W/L ratio is 6250 for the ΙΟμιη spaced electrodes and 3125 for the 20μιη spaced electrodes.
4. Film preparation with ligand exchange on film
The nanoparticles are dispersed in a mixture of hexane and octane (9: 1 as volume ratio). The electrodes are warmed at 125°C on a hot plate for two minutes and then thermalized at room temperature. The solution is dropcasted onto the interdigitated electrodes. The typical thickness for a film is 30nm. Then the film is dipped in a Na2S solution dispersed in ethanol ([Na2S]=l-5g.L_1) for 1 minute for PbS and PbSe and 30 s for HgTe. The film is then rinsed in pure ethanol. Finally the film is annealed at 80°C for one minute.
4' . Film preparation with ligand exchange in solution
For a typical ligand exchange 15mg of Na2S are dissolved in 0.5ml of N methyl formamide (NMFA) by sonication. Then 1ml of the solution of nanoparticles in a non- polar solvent is added. The mixture is then stirred up to the point where the nanoparticles get dissolved in the polar phase. Then 2ml of hexane is added, and after sonication the non-polar phase is removed. This step is repeated a second time. Finally the nanoparticles are precipitated by addition of acetonitrile, after the centrifugation the solid is redispersed in NMFA.
This solution is dropcasted on the electrodes on a hot plate at 100°C. The heating is performed 10 minutes more than requested to dry the film. The typical thickness for a film is 40nm.
5. Transistor preparation
First the electrolyte is softened by warming it on a hot plate at 80°C. To obtain a transistor, the electrolyte is brushed on the film of nanoparticles processed with the S " ligand exchange. Typical thickness is around 1mm. The device is finally degased under vacuum for at least 20min at room temperature. Finally a metallic contact is deposited on the electrolyte as a gate electrode.
5a. Dual gate transistor
The system is the same as described in 5. but the substrate is a two layers system composed a conductive layer such as doped Si and a dielectric (insulating) layer such as Si02, Hf02 or non-conductive polymer. The system is a four electrodes terminal comprising: one drain and one source to bias the channel made of the nanoparticles, one gate electrodes to connect the electrolyte and one substrate electrode to connect to the conductive layer of the substrate. The gate electrodes is used to strongly modulate the carrier density, while the substrate electrode is used to obtain a fast carrier density modulation.
The following table lists the different materials synthetized and used in FET device of the present invention, the size and shape of the synthetized particle, the on/off ratio of the FET based on film of them, the gate bias range over which the FET operates, the gate capacitance per unit area (C∑), and the subthreshold slope. Material Shape - size (nm) Conduction On/off Gate bias Subthreshold behavior ratio range (V) slope
(mV/decade)
PbS Sphere - 6.5 ambipolar 4. 102 ±3 215 (at 2.6V)
PbS Cube - 10 ambipolar 6. 102 ±3 330 (at 1.8V)
PbSe Sphere - 6.5 ambipolar 3.3 102 ±3.4 350 (at 1.8V)
HgTe Tetrahedron -8 ambipolar 1.5 104 ±2 150 (at-0.8V)
CdSe Sphere - 4 n 1.4 10s ±3.5 220 (at 1.9V)
CdS Rods - 4x80 n 104 ±3.5 300 (at 1.4V)
CdTe Platelets - 30x100 P 2 103 ±3.5 600 (at -IV)
CdSe/CdS Platelets - 20x15 n 109 ±2.5 80 (at 1.2V)
The aforementioned results are obtained for a thickness inferior to 100 nm; thicker film may have better capacitance.
5b- 1. Phototransistor preparation
For phototransistor we used the same system as describe for transistor. Nevertheless the electrodes are deposited on a transparent substrate at the wavelength of detection such as glass in the visible or Si in the mid IR. To increase the absorption the nanoparticle film can be obtained using a multilayer approach. The film deposition and ligand exchange steps are repeated several times, up to the point where the film thickness reach the desired value, typically in the 30nm to 3μιη range. 5b-2. Phototransistor preparation with CdSe quantum dots
The electrolyte is softened by warming it on a hot plate at 100°C. The nanoparticles are capped with S " ligands with one of the method describe is example 4. Electrodes are prepared on glass substrate according to the method of example 3. The nanoparticle solution is dropcasted on the electrodes on a hot plate at 100°C and then annealed quickly at 220°C for 2 min in a Ar filled glove box. To obtain a phototransistor, the electrolyte is brushed on the film of nanoparticles processed with the S " ligand exchange. Typical thickness for the electrolyte is around 1mm. The device is finally let cooled down to room temperature either under vacuum or under inert atmosphere. Finally a metallic contact is deposited on the electrolyte as a gate electrode. 5b-3. Phototransistor preparation with CdSe/CdS nanoplatelets
The electrolyte is softened by warming it on a hot plate at 100°C. The nanoparticles are capped with S " ligands with one of the method describe is example 4. Electrodes are prepared on glass substrate according to the method of example 3. The nanoparticle solution is dropcasted on the electrodes on a hot plate at 120°C and then annealed quickly at 200°C for 2 min in a Ar filled glove box. To obtain a phototransistor, the electrolyte is brushed on the film of nanoparticles processed with the S " ligand exchange. Typical thickness for the electrolyte is around 1mm. The device is finally let cooled down to room temperature either under vacuum or under inert atmosphere. Finally a metallic contact is deposited on the electrolyte as a gate electrode.
5b-4. Phototransistor preparation with PbS or PbSe quantum dot
The electrolyte is softened by warming it on a hot plate at 100°C. The nanoparticles are capped with S " ligands with one of the method describe is example 4. Electrodes are prepared on sapphire substrate according to the method of example 3. The nanoparticle solution is dropcasted on the electrodes on a hot plate at 80°C and then annealed quickly at 100°C for 2 min in a Ar filled glove box. To obtain a phototransistor, the electrolyte is brushed on the film of nanoparticles processed with the S " ligand exchange. Typical thickness for the electrolyte is around 1mm. The device is finally let cooled down to room temperature either under vacuum or under inert atmosphere. Finally a metallic contact is deposited on the electrolyte as a gate electrode.
5b-5. Phototransistor preparation with HgTe quantum dot
The electrolyte is softened by warming it on a hot plate at 100°C. The nanoparticles are capped with S " ligands with one of the method describe is example 4. Electrodes are prepared on undoped silicone substrate according to the method of example 3. The nanoparticle solution is dropcasted on the electrodes on a hot plate at 80°C and then annealed quickly at 100°C for 2 min in a Ar filled glove box. To obtain a phototransistor, the electrolyte is brushed on the film of nanoparticles processed with the S " ligand exchange. Typical thickness for the electrolyte is around 1mm. The device is finally let cooled down to room temperature either under vacuum or under inert atmosphere. Finally a metallic contact is deposited on the electrolyte as a gate electrode.
5b-6. Phototransistor preparation with CdS rods or ZnSe quantum dot
The electrolyte is softened by warming it on a hot plate at 100°C. The nanoparticles are capped with S " ligands with one of the method describe is example 4. Electrodes are prepared on quartz substrate according to the method of example 3. The nanoparticle solution is dropcasted on the electrodes on a hot plate at 120°C and then annealed quickly at 250°C for 2 min in a Ar filled glove box. To obtain a phototransistor, the electrolyte is brushed on the film of nanoparticles processed with the S " ligand exchange. Typical thickness for the electrolyte is around 1mm. The device is finally let cooled down to room temperature either under vacuum or under inert atmosphere. Finally a metallic contact is deposited on the electrolyte as a gate electrode.
5c. Bicolor Phototransistor / photodetector preparation
Large interdigitated electrodes (1cm ) are used as substrate. In the upper area CdTe quantum dots (p type layer) capped with S " ligands and dispersed in NMFA is dropcasted on the electrodes on a hot plate at 100°C. Once the system is dried CdSe/CdS nanoplatelets (n type layer) are deposited using the same process on the lower area of the electrodes. The electrolyte is then brushed on the whole device. Depending on the sign of the gate bias, only the p or n layer leads to a significant contribution to the current.
5d. Bicolor Phototransistor / photodetector preparation using hybrid approach
Large interdigitated electrodes (1cm ) are used as substrate. A solution of poly(3-hexylthiophene) (P3HT) is prepared by mixing 30mg/ml of P3HT solid in chloroform. In the upper area the P3HT solution is deposited (p type layer) on the electrodes on a hot plate at 100°C. Once the system is dried CdSe/CdS nanoplatelets (n type layer) are deposited using the same process on the lower area of the electrodes. The electrolyte is then brushed on the whole device. Depending on the sign of the gate bias, only the p or n layer leads to a significant contribution to the current.
5e. Bicolor Phototransistor / photodetector preparation using multipixel approach
Interdigitated electrodes (0.3cm ) prepared on transparent substrate at the two wavelength which aim to be detected are used as substrate. A solution of HgTe quantum dot dispersed in hexane:octane (9: 1 as volume ratio) is dropcasted on one of the electrode. On a second set of electrodes CdSe/CdS nanoplatelets are deposited by dropcatsing on a hot plate at 100°C. The electrolyte is then brushed on one of the two pair of electrodes. Then the two pair of electrodes are electrically connected to obtain one source and one drain electrode. The gate bias is used to tune the gain of the nanoplatelets film.
5f . Multicolor Phototransistor / photodetector preparation
Large interdigitated electrodes (1cm ) are used as substrate. Solution of nanoparticles (HgTe, quantum dot, PbS quantum dot, CdS nanorods and CdSe/CdS nanoplatelets) with different band gaps capped with S " and dispersed in NMFA are dropcasted on the electrodes on a hot plate at 100°C at different position. The electrolyte is then brushed on the whole device. Depending on the value of the gate bias only some materials lead to a significant contribution to the current.
Responsivity A phototransistor according to the present invention is characterized under the following condition. CdSe/CdS nanoplatelets coated with S " capping ligands have been deposited on interdigitated drain source electrodes. The measurements are made at room temperature under secondary vacuum. The applied drain source is 1 V. The applied gate bias is 1 V. The sample is illuminated using a 405 nm with a power between 1 and 50 mW. The obtained photoresponse is ranging from 1 to 10 mA.W"1. Pn junction formation
Some HgTe quantum dots are capped using S " ligands, using a phase transfer method using Na2S precursor dissolved in N-methyl formamide. The nanoparticle solution is dropcasted on electrodes. Electroltrolyte made of L1CIO4 dissolved in PEG (Mw=6000g.mol"1) is brushed on the nanoparticle film, while the electrolyte has been soften at 90°C. A gate electrode is deposited on the electrolyte and grounded. A source bias of 2V compared to the gate is applied and a drain bias of -2V compared to the gate is also applied while using a two channel sourcemeter. The whole system is frozen by cooling the system to a temperature below the freezing point of the electrolyte. Then a stable pn junction is formed showing a current-voltage characteristic of a diode.

Claims

1. A photodetector comprising a substrate, at least three electrodes, an active material comprising a plurality of inorganic semiconductor nanoparticles bridging at least two electrodes and an electrolyte.
2. The photodetector according to claim 1, wherein the substrate and/or the electrolyte are transparent in at least a wavelength window compatible with the absorption spectrum of the plurality of nanoparticles
3. The photodetector according to claims 1 or 2, wherein said nanoparticles are nanocrystals, nanosheets, nanorods, nanoplatelets, nanoparticles, nanowires, nanopowders, nanotubes, nanotetrapods, nanoribbons, nanocubes, quantum dots and/or combinations thereof.
4. The photodetector according to anyone of claims 1 to 3, wherein said electrolyte is liquid, polymer, ion-gel or solid.
5. The photodetector according to anyone of claims 1 to 4, wherein said photodetector is a phototransistor.
6. The photodetector according to anyone of claims 1 to 5, wherein the at least two electrodes bridged by a plurality of inorganic semiconductor nanoparticles are spaced by a nanogap whose size ranges from 1 nanometer to 1 micrometer.
7. The photodetector according to anyone of claims 1 to 6, wherein the photodetector comprises at last two pluralities of various nanoparticles which can be independently addressed using the gate voltage as a switch.
8. The photodetector according to anyone of claims 1 to 7, wherein bulk charging is achieved within said active material comprising a plurality of nanoparticles.
9. The photodetector according to anyone of claims 1 to 8, wherein said active material comprising a plurality of nanoparticles has a thickness from 10 nanometers to 1 centimeter, preferably from 10 nanometers to 10 micrometers, more preferably from 10 nanometers to 1 micrometer.
10. A method for producing photodetector according to anyone of claims 1 to 9, the method comprising:
a) the deposition of the first and the second electrodes onto a substrate, b) he preparation of a solution of nanoparticles,
b') the nanop article's ligand exchange step in solution,
c) the deposition of the previous solution of nanoparticles onto the electrodes and substrate,
c') if step b') is not implemented, the nanop article's ligand exchange step on the active material comprising a plurality of nanoparticles,
d) the electrolyte deposition on the active material comprising a plurality of nanoparticles,
e) the third electrode deposition on the electrolyte.
11. The method according to claim 10, wherein said deposition of nanoparticles is achieved by drop casting or spin coating, dip coating, spray casting, screen printing, inkjet printing, sputtering techniques, evaporation techniques electrophoretic deposition, or vacuum methods.
12. A photodetector operating as in photovoltaic mode or a LED, comprising the photodetector according to anyone of claims 1 to 9, wherein a pn junction is formed between two of the electrodes.
13. An array comprising a plurality of photodetectors according to anyone of claims 1 to 9.
14. The array of photodetectors according to claim 12, wherein a readout circuit is connected to the plurality of photodetectors.
15. The array of photodetectors according to anyone of claims 12 or 13, wherein the plurality of photodetectors comprises a first plurality of photodetectors and a second plurality of photodetectors and wherein the band gap of the first plurality of photodetectors is different from the band gap of the second plurality.
16. A focal plane array for use in an imaging device comprising an array of photodetectors according to anyone of claims 12 to 14.
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