EP2898530A1 - Dispositif photodétecteur moléculaire à assemblage automatique - Google Patents

Dispositif photodétecteur moléculaire à assemblage automatique

Info

Publication number
EP2898530A1
EP2898530A1 EP13801772.8A EP13801772A EP2898530A1 EP 2898530 A1 EP2898530 A1 EP 2898530A1 EP 13801772 A EP13801772 A EP 13801772A EP 2898530 A1 EP2898530 A1 EP 2898530A1
Authority
EP
European Patent Office
Prior art keywords
layer
photo
electrode layer
dye
detector device
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP13801772.8A
Other languages
German (de)
English (en)
Inventor
Mario Caironi
Annamaria PETROZZA
Lorenzo CARANZI
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Fondazione Istituto Italiano di Tecnologia
Original Assignee
Fondazione Istituto Italiano di Tecnologia
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Fondazione Istituto Italiano di Tecnologia filed Critical Fondazione Istituto Italiano di Tecnologia
Publication of EP2898530A1 publication Critical patent/EP2898530A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K39/00—Integrated devices, or assemblies of multiple devices, comprising at least one organic radiation-sensitive element covered by group H10K30/00
    • H10K39/30—Devices controlled by radiation
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K10/00—Organic devices specially adapted for rectifying, amplifying, oscillating or switching; Organic capacitors or resistors having potential barriers
    • H10K10/701—Organic molecular electronic devices
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
    • H10K85/30—Coordination compounds
    • H10K85/341—Transition metal complexes, e.g. Ru(II)polypyridine complexes
    • H10K85/344—Transition metal complexes, e.g. Ru(II)polypyridine complexes comprising ruthenium
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
    • H10K85/60—Organic compounds having low molecular weight
    • H10K85/631—Amine compounds having at least two aryl rest on at least one amine-nitrogen atom, e.g. triphenylamine
    • 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

Definitions

  • the present invention relates generally to electronic devices, and more specifically to a photo-detector device according to the preamble to Claim 1.
  • a photo-detector device is a device capable of detecting incident optical radiation, supplying an electrical signal at the output having a current intensity or a potential difference proportional to the intensity of the radiation detected.
  • the fabrication of a molecular electronic circuit requires the fabrication of devices based on junctions in which a functional molecular layer is included between a pair of conducting electrodes connected to the rest of the circuit.
  • organic photo-detector devices are not known in the literature in which an exci- ton may be separated into free charge carriers which may be injected into an electrical circuit, when a functional layer composed of a single molecular layer is interposed directly between two electrodes.
  • Such a structure has for example been used in the fabrication of rectifier and switching devices.
  • These compounds possess two distinct isomers, of conjugated and non-conjugated form, respectively, which exhibit electrical conductivities different by 1-2 orders of magnitude.
  • the conductance of the device can be con- trolled optically, in a completely reversible manner, taking advantage of the photo- isomerization properties of the compound.
  • This device does not possess photo-detecting properties per se, since it is not capable of supplying an electrical signal at the output having a current intensity proportional to the intensity of an incident optical radiation.
  • the property of varying the electrical conductivity depends on the form that the molecule assumes at a specific range of wavelengths, but in the device no generation of charge carriers takes place at the operating wavelength.
  • the charge carriers which pass through the device under the conduction operating condition are injected from an external circuit.
  • organic photovoltaic cells are also known (DSSC, dye-sensitized solar cells, also known as Graetzel cells), in which organic dye substances capture photons of optical radiation generating excitons which dissociate at the interface with an oxide layer, releasing by diffusion an electron which is injected into the associated anode electrode contact via a charge transport mechanism, and in which an electrolyte including a redox pair regenerates the dye releasing to it its own electron, that in turn it receives from a cathode electrode.
  • DSSC dye-sensitized solar cells, also known as Graetzel cells
  • Organic photovoltaic cells are devices on the mesoscopic scale, whose complex structure is difficult to integrate with a fabrication technology for integrated electronic circuits.
  • the process of fabrication of organic photovoltaic cells requires high temperatures, which involves the selection of substrates compatible with such temperatures, limiting the level of applicability and integration.
  • a further drawback of organic photovoltaic cells comes from the intrinsic slowness of the electrical response, associated with the charge transport phenomena within the bulk of the device.
  • the aim of the present invention is thus to provide a molecular photo-detector device capable of supplying an electrical signal proportional to the intensity of an incident optical radiation.
  • the invention furthermore aims to provide a photo-detector device having a non- complex layered structure that can be integrated with a fabrication technology for integrated electronic circuits.
  • a further subject of the invention is a photo-detection arrangement as claimed.
  • the present invention is based on the principle of fabricating a photo-detector device by means of a functional layer of conjugated organic molecules, for example comprising a donor group and an acceptor group, which is included between a pair of electrical conductors, of which at least one is a (semi)-transparent electrode, arranged for connecting to downstream electronic signal processing means.
  • the functional layer of organic molecules is preferably a self-assembling molecular monolayer of an organic dye, bonded to a conducting electrode including a layer of bonds having anchoring sites capable of promoting a chemical bond with anchoring groups of the dye molecules, for example a thin layer of native oxide of the electrode metal, capable of bonding itself with -COOH groups of the dye.
  • Spectral measurements of a photo-current in the device have demonstrated that the rise time of the photo-current corresponds to the photonic absorption time of the molecules, whereby the photo-generation mechanism is substantially correlated to the opto-electronic properties of the molecular layer.
  • the photo-detector device may advantageously be scaled proportionally and integrated into a complex electronic circuit since its fabrication requires simple processing steps for the deposition of the materials.
  • the possibility of operating in photovoltaic mode without a polarizing electric field applied to the electrodes allows the device, subject of the invention, to detect optical signals with a high signal/noise ratio with respect to solid state photo-detection devices.
  • Figure 1 shows schematically a cross section of a structure of a photo-detector device according to the invention
  • Figure 2 shows schematically a cross section of a portion of the structure of a photo- detector device according to the invention, highlighting the photo-detection mechanism
  • Figures 3a, 3b, 3c and 3d are chemical structures of four dye substances preferred as functional molecular layer for a photo-detector device according to the invention
  • Figures 4a-4c are diagrams of I-V characteristic curves of a photo-detector device according to the invention.
  • Figure 5 is a diagram representing the behaviour of a photo-current over time as a function of the illumination conditions for a photo-detector device according to the invention
  • Figure 6 is a comparison diagram between the I-V characteristic curves of a photo- detector device according to the invention with various dye substances for the functional layer, as a function of the illumination conditions;
  • Figure 7 shows a schematic photo-detection circuit arrangement comprising a photo- detector device according to the invention.
  • Figure 1 shows one embodiment of a photo-detector device, subject of the invention, indicated overall with 10.
  • the embodiment in Figure 1 is substantially based on a configuration of a molecular junction with a large surface area, analogous to that provided in the prior art and adopted by A. J. Kronemeijer et al. in "Reversible Conductance Switching in Molecular Devices", Adv. Mater. 2008, Vol. 20, pp. 1467-1473 for the fabrication of molecular switches based on the photochromic properties of some organic molecules.
  • the device comprises a lower electrode 20 of aluminium deposited on a substrate (not shown), on which is grown a thin native oxide layer (A10 x ) 22 able to form anchoring sites for a functional molecular layer.
  • the oxide layer is grown, for example, by thermal evaporation of the surface layers of the electrode and exposure to air.
  • the functional (active) molecular layer is a single molecular layer (monolayer) of a photo-active organic substance, such as an organic dye substance, preferably self-assembling, comprising at least one conjugated part which includes a donor group and an acceptor group responsible for the absorption of an optical radiation, and an anchoring part which includes a bonding group such as for example a thiol, a phosphonic acid, a carboxyl group which promote the bonding of the molecule onto specific surfaces (amongst which are oxides, but also metals, semiconductors, etc.).
  • a photo-active organic substance such as an organic dye substance, preferably self-assembling, comprising at least one conjugated part which includes a donor group and an acceptor group responsible for the absorption of an optical radiation, and an anchoring part which includes a bonding group such as for example a thiol, a phosphonic acid, a carboxyl group which promote the bonding of the molecule onto specific surfaces (amongst which are oxides, but also metal
  • the functional molecular layer 24 comprises a dye substance with -COOH anchoring group, capable of implementing a self- assembly of the molecules on the native oxide layer of aluminium 22 following a deposition process from a liquid phase or from a vapour phase.
  • the functional molecular layer 24 is bounded laterally by a thicker inert polymer layer 26, preferably a layer of photoresist.
  • the functional layer 24 is conventionally formed by deposition of the molecular substance into a cavity obtained via a photolithographic process of the inert polymer layer 26 previously deposited, by which a volume of photoresist is removed from a predefined area by means of masking while the subsisting photoresist is chemically stabilized.
  • the cavity is preferably of circular shape and with a diameter in the range preferably between 1 micron and 1 millimetre, depending on the circuit requirements.
  • a second electrode (or upper electrode) 28 is formed from (semi-)transparent conducting polymer, preferably PEDOT:PSS, over one area of which a metal contact 30 is deposited, for example gold, in order to reduce the resistivity of the polymer electrode.
  • Figure 2 shows schematically a region of the device in which a single molecule of the functional monolayer 24 is shown, in order to highlight the photo-detection mechanism.
  • the molecule is the commercial dye D102, whose basic formula is C 37 H 3 oN 2 0 3 S 2 , marketed by ⁇ UK LIMITED.
  • D and A respectively indicate the donor group and the acceptor group of the molecule and, in conjunction with these, the transfer of a hole (h + ) and of an electron (e " ) to the respective electrodes are furthermore shown.
  • the acceptor group A is bonded to a carboxyl anchoring group and is disposed in contact with the lower electrode 20 made of aluminium, and the donor group D is disposed in contact with the upper polymer electrode 28 by virtue of the rigidity of the molecule itself.
  • the molecule When the molecule absorbs a photon (hv) through the (semi-)transparent electrode 28, it assumes a charge transfer state in which an exciton is generated on the conjugated part of the molecule, in other words a weakly-coupled electron-hole pair, which respectively resides on the acceptor group A and on the donor group D.
  • the donor group and the acceptor group are disposed within the molecule in such a manner that the excitation induced by an incident optical radiation generates an intra-chain charge transfer state and the charge carriers are easily separated, whereby the electron is rapidly injected into the lower electrode 20 through the anchoring layer 22 (in a time typically less than lOOps), whereas the hole is rapidly injected into the upper electrode 28.
  • the charge carriers thus give rise to an electrical current flow in an external circuit connectable across the photo-detector device, supplying the detection information of the optical radiation.
  • the current-voltage (I-V) characteristic curves have been measured under dark conditions (curve D) and under conditions of illumination (curve L) for a photo-detector device with a functional layer comprising the dye D102, clearly detecting a photo-current, as shown in Figures 4a-4c.
  • Figure 4a shows the behaviour of the current- voltage (I-V) curves by means of a comparison between the dark condition and condition of illumination over a range of bias voltages between -IV and +1V.
  • Figure 4b shows an enlargement of the behaviour of the current-voltage (I-V) curves in Figure 4a over a range of bias voltages around 0V.
  • the characteristic curves of Figure 4a are shown with a semi-logarithmic current scale.
  • a weak current is measured determined by the injection of holes into the lower electrode, this being a condition inhibited by the topology of the device, in particular by the arrangement of the donor and acceptor groups of the molecules of the functional layer with respect to the electrodes.
  • Figure 5 shows the time response of the device, subject of the invention, to a series of light pulses.
  • the device responds promptly generating a detection current, whose rising edge shown in the figure is limited exclusively by the integration time of the measurement.
  • the structure of the photo-detector device of the invention opens up the way to the production of ultra-small-scale photo-detection devices, which devices may be easily integrated, by virtue of the auto-assembling properties of the organic layer that does not require particular processing phases, into photo-detection circuit arrangements and, more generally, into opto-electronic systems (lab-on-chip where the local detection of optical signals is re ⁇ quired, for example emissions of markers associated with analyses) fabricated with fabrication technologies for conventional solid state electronic circuits.
  • a photo-detector device may be integrated into a photo- detection circuit arrangement illustrated in Figure 7.
  • elements or components identical or functionally equivalent to those illustrated in Figure 1 have been indicated with the same references already used in the description of such preceding figures.
  • a biasing potential difference is applied to the electrodes of the molecular photo-detector device 10 between a first biasing terminal Bl and a second biasing terminal B2.
  • Signal terminals SI and S2 are associated with these same electrodes of the device for the connection of the device to the rest of an electronic circuit, for example to a complex signal processing electronic circuit P, downstream of the photo-detector device.

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  • Light Receiving Elements (AREA)
  • Fire-Detection Mechanisms (AREA)

Abstract

Cette invention concerne un dispositif photodétecteur comprenant une couche active conçue pour absorber le rayonnement optique et pour générer de manière correspondante des paires de porteurs de charge électrique. Ladite couche est disposée entre une première et une seconde couche d'électrode comprenant un matériau conducteur respectif. Au moins une desdites couches d'électrode est une couche de matériau optiquement transparent conçue pour être reliée à un circuit externe de traitement de signaux électriques. Ladite couche active comprend une monocouche de molécules à assemblage automatique, comprenant un groupe donneur orienté vers la première couche d'électrode et un groupe accepteur orienté vers la seconde couche d'électrode, lesdites molécules étant adaptées assumer un état de transfert de charge résultant de l'absorption du rayonnement optique, les porteurs de charge générés résidant séparément sur le groupe donneur et sur le groupe accepteur et étant transférés à partir de ceux-ci vers les couches d'électrode adjacentes, de manière à déterminer un flux d'un courant électrique de détection dans le circuit de traitement de signaux.
EP13801772.8A 2012-09-24 2013-09-23 Dispositif photodétecteur moléculaire à assemblage automatique Withdrawn EP2898530A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IT000826A ITTO20120826A1 (it) 2012-09-24 2012-09-24 Dispositivo foto-rivelatore molecolare auto-assemblante.
PCT/IB2013/058776 WO2014045256A1 (fr) 2012-09-24 2013-09-23 Dispositif photodétecteur moléculaire à assemblage automatique

Publications (1)

Publication Number Publication Date
EP2898530A1 true EP2898530A1 (fr) 2015-07-29

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Application Number Title Priority Date Filing Date
EP13801772.8A Withdrawn EP2898530A1 (fr) 2012-09-24 2013-09-23 Dispositif photodétecteur moléculaire à assemblage automatique

Country Status (3)

Country Link
EP (1) EP2898530A1 (fr)
IT (1) ITTO20120826A1 (fr)
WO (1) WO2014045256A1 (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9786855B2 (en) 2014-12-30 2017-10-10 Indian Institute Of Technology Bombay Micro electro mechanical system (MEMS) based wide-band polymer photo-detector

Family Cites Families (3)

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Publication number Priority date Publication date Assignee Title
CA1229221A (fr) * 1984-05-02 1987-11-17 James R. Bolton Jonction p-n organique avec antenne
FI120757B (fi) * 2004-08-18 2010-02-15 Licentia Oy Vektoriaaliseen elektroninsiirtoon perustuva valosähköinen kenno
GB2432718A (en) * 2005-11-25 2007-05-30 Seiko Epson Corp Multicolour metal oxide electrochemical cell

Non-Patent Citations (1)

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Title
See references of WO2014045256A1 *

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WO2014045256A1 (fr) 2014-03-27
ITTO20120826A1 (it) 2014-03-25

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