CN111740019A

CN111740019A - Halide perovskite photoelectric device based on polar interface

Info

Publication number: CN111740019A
Application number: CN202010503089.9A
Authority: CN
Inventors: 连亚霄; 赵保丹; 狄大卫; 理查德·亨利·弗兰德; 崔林松
Original assignee: Zhejiang University ZJU
Current assignee: Zhejiang University ZJU
Priority date: 2020-06-05
Filing date: 2020-06-05
Publication date: 2020-10-02

Abstract

A halide perovskite photoelectric device based on a polar interface belongs to the technical field of novel energy, materials and electronics. The present invention is directed to a polar interface based halide perovskite optoelectronic device that efficiently matches perovskite material and charge transport material together through a polar interface material. The preparation process of the perovskite luminescent thin film luminescent device comprises the following steps: preparing a substrate with a polar interface; and transferring the substrate with the evaporated polar interface to a glove box filled with high-purity nitrogen to spin-coat the perovskite thin film to obtain the perovskite light-emitting thin film light-emitting device. The invention introduces a polar interface in the preparation process of the perovskite material and the photoelectric device, so that the charge transport material with excellent performance and the perovskite material are mutually compatible and effectively matched, the interface can regulate and control the potential barrier of the charge transport material and the perovskite, and can regulate and control the crystallization process of the perovskite on the substrate or the transport material to regulate and control the crystallization quality, and finally, the performance of the perovskite material and the photoelectric device is optimized or regulated and controlled.

Description

Halide perovskite photoelectric device based on polar interface

Technical Field

The invention belongs to the technical field of novel energy, materials and electronics.

Background

The metal halide perovskite as a material processed by a solution method has remarkable photoelectric characteristics, including the advantages of high carrier mobility, long carrier diffusion length, adjustable band gap, high luminous efficiency, ultra-narrow luminous bandwidth and the like. With the rapid development of halide perovskite materials, the excellent properties of perovskites have made great progress in many applications, such as photovoltaic devices, e.g., solar cells, photodetectors, light emitting diodes, etc. After the first perovskite solar cell is reported in 2009, the perovskite material is rapidly developed in the field of solar cells, and the energy conversion efficiency of the perovskite material already exceeds 25% in 2019. After the first perovskite light emitting device was reported in 2014, the performance of the perovskite-based light emitting device was rapidly improved in less than 5 years, and the external quantum efficiency thereof was already 20% in 2018. The rapid development of the performance of the device is due to the fact that perovskites are paid extensive attention by researchers in multiple fields, people are dedicated to improving the overall performance of perovskite materials, at present, perovskite devices absorb the precious experience of multiple research fields, including organic light emitting diodes, quantum dot light emitting diodes, semiconductor polycrystalline silicon batteries, lithium batteries, high polymer materials and other fields, surface passivation and modification are carried out on the perovskites and transmission materials through various efforts, the device can effectively inhibit non-radiative recombination inside the device and enhance radiative recombination, and therefore the performance of the device is greatly improved.

At present, the structure of the device is also developed from the most initial sandwich functional layer to a multilayer functional layer, taking a five-layer structure as an example, the five-layer structure respectively comprises an electrode, a hole transport material (electron blocking material), a luminescent material (absorbing material in a battery), an electron transport material (hole blocking material), and an electrode. The selection of functional materials has a positive effect on the improvement of device performance, but materials with excellent performance in other fields cannot be directly applied to the perovskite device structure, and active improvement is still needed to adapt to the perovskite device structure, for example, the mutual dissolution phenomenon of solvents and solutes among a plurality of functional materials involved in the processing of the perovskite light-emitting device by a solution method is a problem to be solved.

For functional materials with outstanding performance in the field of currently reported OLEDs, more materials still can not be used for directly preparing high-performance perovskite LEDs by a solution method, and further optimization is needed when the materials are applied to the field of perovskites. For the hole transport material conjugated polymers TFB, Poly-TPD and PFO having strong hydrophobicity, it is difficult to deposit halide perovskite thereon in a solution method, such as in the process of manufacturing a light emitting diode. Researchers have employed a variety of methods to achieve efficient deposition of perovskites onto conjugated polymers, one method being surface treatment of the surface of hole transport materials such as TFB, Poly-TPD, etc. by a Plasma cleaner or UV-Ozone cleaner prior to perovskite deposition, thereby changing the surface of the hole transport material from hydrophobic to hydrophilic. However, the surface treatment using plasma causes damage to the polymer surface and thus causes deterioration of the conductive characteristics. Another method is to deposit perovskite after very thin PVK is deposited on a conjugated polymer, but PVK can be dissolved in DMF and DMSO, but DMF and DMSO are very common perovskite precursor solutions, which can cause the perovskite to dissolve part of PVK when deposited on PVK, cause PVK and perovskite to form a blending interface, cause the perovskite growth quality to be influenced, introduce interface defects and crystal growth defects, and further limit the reliability and stability in the device preparation process.

Disclosure of Invention

The present invention is directed to a polar interface based halide perovskite optoelectronic device that efficiently matches perovskite material and charge transport material together through a polar interface material.

The preparation process of the perovskite luminescent thin film luminescent device comprises the following steps:

preparation of the substrate: firstly, respectively carrying out ultrasonic cleaning for 15 minutes by using seven steps of deionized water, acetone, isopropanol, deionized water and isopropanol, then putting the substrate into a UV-Ozone cleaning machine for carrying out Ozone cleaning for 15 minutes, then transferring the substrate into a vacuum coating machine for carrying out polar interface evaporation, wherein the evaporation process in the vacuum coating machine is finished in a glove box, and obtaining the substrate with the polar interface after evaporation;

and transferring the substrate with the evaporated polar interface to a glove box filled with high-purity nitrogen to spin-coat the perovskite thin film: when the perovskite is coated in a spin mode, the substrate coated with the polar interface in a vapor deposition mode is placed on a vacuum spin coating machine, the perovskite precursor solution absorbed by a liquid transfer gun is dripped onto the substrate coated with the polar interface in a vapor deposition mode, the vacuum spin coating machine carries out spin coating for 60s at the rotating speed of 3000 rpm/s, then the substrate coated with the perovskite in a spin mode is placed on a hot bench to be annealed for 10min at the temperature of 60 ℃, and the perovskite luminescent thin film luminescent device is obtained.

The polar interface material of the present invention is composed of a plurality of compounds, including polar interface materials capable of forming compounds during different periods, polar interface materials capable of forming compounds between different groups, strongly polar interface materials capable of forming compounds between different groups, and other interface materials cooperating with perovskite materials.

The polar interface material capable of forming compounds during different periods of the invention comprises a metal oxide material interface ZrO₂、V₂O₅、Al₂O₃、NiO、MoO₃、ZnO、MgO、NiO、SnO₂(ii) a The polar interface material capable of forming compound between different groups comprises carbonate metal compound material Li₂CO₃、Na₂CO₃、 Cs₂CO₃(ii) a The strong polar interface materials which can form compounds among different groups comprise metal fluoride material interfaces LiF, NaF, KF, RbF, CsF and MgF₂、CaF₂(ii) a Other interface materials that interact with perovskite materials include PTFE, piezoelectric films, piezoelectric ceramics.

The invention prepares the conductive perovskite luminescent thin film luminescent device with ITO:

a. conductive substrate with ITO: sputtering an ITO raw material onto a substrate by using a magnetron sputtering technology, placing the substrate on a substrate table with a mask plate, partially shielding the substrate by using the mask plate, and partially sputtering an ITO material to be exposed;

b. cleaning treatment of a conductive substrate: carrying out pretreatment on a conductive substrate, firstly carrying out ultrasonic cleaning for 15 minutes by using seven steps of deionized water, acetone, isopropanol, deionized water and isopropanol, and then putting the conductive substrate into a UV-Ozone cleaning machine for carrying out Ozone cleaning for 15 minutes;

c. preparing a charge transport material film: placing the cleaned conductive substrate into a glass culture dish, conveying the glass culture dish into a nitrogen glove box through a transition bin of the glove box, then placing the conductive substrate on a vacuum spin-coating machine in the nitrogen glove box, dissolving a charge transfer material in a solvent, sucking a charge transfer material solution by using a liquid-moving gun, uniformly coating the charge transfer material solution on the conductive substrate, completely coating ITO (indium tin oxide) by using the charge transfer material, starting a button of the vacuum spin-coating machine to spin-coat at 3000rpm for 60s to form a film of the charge transfer material, after the spin-coating of the film of the charge transfer material is completed, placing the conductive substrate covered with the charge transfer material on a heating table to perform high-temperature annealing at 120 ℃ for 10min, and finally forming the ITO-coated charge transfer material film on the conductive substrate;

d. evaporating polar interface materials: opening a bin gate of the vacuum coating machine in the glove box in the first step, placing the conductive substrate which is taken down from the hot table and is prepared with the charge transmission material into a glass culture dish, conveying the conductive substrate into the glove box with the vacuum coating machine through a transition bin, taking out the conductive substrate prepared with the charge transmission material, placing the conductive substrate on an evaporation substrate table in the vacuum coating machine, adjusting the position of the evaporation substrate table, and closing a baffle below the substrate table;

e. spin coating a halide perovskite thin film: during spin coating, placing a conductive substrate coated with a polar interface material and a charge transport material by evaporation on a vacuum spin coating machine, uniformly coating a halide perovskite precursor solution absorbed by a liquid transfer gun on the conductive substrate coated with the polar interface material and the charge transport material by evaporation, starting a button of the vacuum spin coating machine, spin-coating for 60s at the rotating speed of 5000rpm to form a halide perovskite thin film, and placing the conductive substrate coated with the halide perovskite, the polar interface material by evaporation and the charge transport material on a hot table for high-temperature annealing at 90 ℃ for 10 min;

f. evaporation of cathode charge transport material: placing the annealed conductive substrate covered with halide perovskite, evaporated with polar interface material and covered with charge transfer material into a glass culture dish, transferring the substrate into a glove box with a vacuum coating machine through a transition bin, taking the substrate out of the glass culture dish, placing the substrate on an evaporation substrate table in the vacuum coating machine, adjusting the position of the evaporation substrate table, and closing a baffle below the substrate table; the evaporation rate of the charge transport material detected by the quartz crystal oscillator plate is displayed by the film thickness instrument, after the evaporation rate of the charge transport material displayed by the film thickness instrument is stable, the evaporation rate is stable at 0.05nm/s, a baffle below a base plate table in a vacuum coating machine is started, and the charge transport material with uniform evaporation rate can be uniformly deposited on a conductive substrate covered with halide perovskite, evaporated with a polar interface material and covered with the charge transport material;

g. evaporating an electrode: after the charge transmission material is evaporated, the charge transmission material is placed on a metal mask plate in a vacuum coating machine, the evaporation rate of an electrode detected by a quartz crystal oscillation plate is displayed through a film thickness meter, after the evaporation rate of the electrode displayed by the film thickness meter is stable, the evaporation rate is stable at 0.2nm/s, a baffle below a base plate table in the vacuum coating machine is opened, and the electrode with uniform evaporation rate is uniformly deposited on a conductive substrate covered with the charge transmission material, halide perovskite, an evaporated polar interface material and the charge transmission material.

The preparation method of the polar interface on the substrate adopts magnetron sputtering, MOCVD, ALD, spraying, printing or chemical synthesis methods, and the thickness range is 0.1 nm-1000 nm.

The invention changes the polarity of the polar interface material by regulating the material with different electronegativity differences, or regulates the non-polar interface to be the polar interface, and finally regulates the final performance of the device by changing the polarity mode of the material interface.

The polar material interface of the invention is applied to various photoelectric devices, including solar cells, light-emitting diodes, detectors, fluorescent films, fluorescent powder, semiconductor transistors, lasers and other photoelectric devices and materials.

The polar material interface can be applied to defining the effective working area of the perovskite material or the device, further defining different working patterns, and can be expanded to be applied to perovskite materials and photoelectric devices based on different patterns.

The invention introduces a polar interface in the preparation process of the perovskite material and the photoelectric device, so that the charge transport material with excellent performance and the perovskite material are mutually compatible and effectively matched, the interface can regulate and control the potential barrier of the charge transport material and the perovskite, and can regulate and control the crystallization process of the perovskite on the substrate or the transport material to regulate and control the crystallization quality, and finally, the performance of the perovskite material and the photoelectric device is optimized or regulated and controlled. The method for regulating and controlling the perovskite material and the photoelectric device by adopting the polar interface can be widely applied to various photoelectric devices and materials, including solar cells, light-emitting diodes, detectors, fluorescent films, fluorescent powder, semiconductor transistors, lasers and other photoelectric devices and materials.

Drawings

FIG. 1 is a perovskite structure of a common substrate polarity interface of the present invention;

FIG. 2 is a polar interface perovskite optoelectronic device structure with an ITO conductive substrate of the present invention;

FIG. 3 is a flow chart of the preparation of the hydrophilicity experiment of the polar interface of the present invention;

FIG. 4 is a comparison of surface tension before and after the addition of an interface according to the present invention;

FIG. 5 is a flow chart of the present invention for surface treatment using a polar interface and plasma, respectively;

FIG. 6 is a topographical view of a charge transport material treated with a polar interface and a plasma surface in accordance with the present invention;

FIG. 7 is a SEM flow chart for viewing a spin-on perovskite luminescent film of the present invention;

FIG. 8 is an SEM image of the film formation morphology of the perovskite of the present invention at different interfaces;

FIG. 9 is a flowchart of a spin-on perovskite luminescent film test wavelet of the present invention;

FIG. 10 is a graph of perovskite luminescence spectra for different materials as interfaces;

FIG. 11 is a flow chart of a spin-on perovskite luminescent thin film test Absorbance;

FIG. 12 is a schematic illustration of the effect on perovskite absorption spectra for different materials as interfaces;

FIG. 13 is a flow chart of a test XRD for spin-on perovskite luminescent films;

FIG. 14 is a thin film XRD spectrum of perovskite at different interfaces;

FIG. 15 is a flow chart of the Photoquantum efficiency PLQE test for different interfaces;

FIG. 16 is a plot of PLQE of perovskites as a function of interfacial electronegativity of different polarities;

FIG. 17 is a flow chart of steps for the preparation of perovskites on different charge transport materials;

FIG. 18 is a graph of the fluorescence lifetime of perovskites on different charge transport materials;

FIG. 19 is a flow chart for the preparation of interfaces of different thicknesses;

FIG. 20 is a graph of the effect of interfaces of different thicknesses on charge injection capability;

FIG. 21 is a flow chart of light emitting diode device fabrication;

fig. 22 is a graph of device efficiency based on polar interfacial transport materials and other transport materials.

Detailed Description

In order to solve the problem of mismatching of two materials in the perovskite, the related research experience in the field of inorganic semiconductors and materials is used for reference. At present, when epitaxial growth is carried out in III-V family inorganic semiconductors, for two different semiconductor materials, the two materials are difficult to directly match due to large difference of lattice parameters, semiconductor heterojunctions can be formed although the two materials can be contacted when the difference of the lattice parameters is small, and a large number of interface states can be generated on the interfaces due to the difference of the lattice constants, so that great influence is generated on the energy band structure and electron transport of the heterojunction. Therefore, in order to eliminate the problem of difficult material growth caused by interface defects and to make good contact between two functional materials, the schottky contact between the two materials can be improved to ohmic contact by introducing a polar material or an active material between the two materials. The introduced polar material or the activated material ensures that the lattice mismatch of the two functional materials is small, the interface state density is low and the interface potential barrier is low, thereby increasing the electron injection and transport capability, so that different materials can be effectively matched by effectively processing the interface. In the metallic glass preparation process, the prepared metallic glass has poor stability due to the fact that the lattices of the glass and the metal are not matched, so that a small amount of transition metal or graphene is introduced between the glass and the metal for lattice matching, and a more stable lattice structure can be realized. Based on the above, for the phenomenon that the charge transport material with excellent performance in perovskite is not matched with the perovskite material, the introduction of a functional material or an activation material can be considered to enable the perovskite material to be effectively matched with the charge transport material, so that the potential barrier of the interface is reduced, and the electron transport capacity is increased.

As the perovskite is a strong polar material, the perovskite can be well matched with the strong polar material according to a similar compatibility principle, and meanwhile, the inherent components of the perovskite cannot be changed by the introduced new material, different strong polar materials are selected as interface materials to be introduced between the charge transmission material and the perovskite material for lattice matching. Different transport materials are needed for the perovskite growing in situ, but the transport material with excellent performance is incompatible with the perovskite, so that charge transport barriers exist on the interface between the perovskite and the transport material, the perovskite can be guaranteed to effectively grow on the polymer hole transport material covered with the polar interface by adopting the ultrathin strong polar material to deposit on the polymer hole transport material, the crystal growth quality can be increased or regulated by adopting the polar material interface, the carrier life of the perovskite film is regulated, and the stability of the film and the performance of a device based on the perovskite are further regulated. The method for regulating and controlling the performance of the perovskite thin film or the device by adopting the polar interface can be applied to other photoelectronic devices, including photoelectronic devices and materials such as solar cells, light-emitting diodes, detectors, fluorescent thin films, fluorescent powder, semiconductor transistors, lasers and the like, so as to prepare devices with more excellent performance.

At present, the perovskite material and the photoelectric device still have defects in the aspects of photoelectric property and stability, and the specific reasons are shown in two aspectsOn one hand, the substrate with outstanding performance, the charge transmission material and the perovskite material cannot be perfectly matched, so that the optimal performance of the prepared perovskite photoelectric device is limited, for example, for the photoelectric device prepared by a solution method, the charge transmission material and the perovskite material have an interface mutual solubility phenomenon, so that the interface is not perfect, and the performance of each functional material is influenced; on the other hand, the perovskite material has problems, such as poor crystal growth quality and more crystal boundary and interface defects, and finally limits the performance of the perovskite material and the photoelectric device. In view of the incompatibility problem between perovskite material and charge transport material, a method commonly used at present is to activate the surface of the charge transport material by using a Plasma surface cleaner or a UV-Ozone surface cleaner, and the surface of the treated charge transport material is activated, but the surface treatment can damage the radical structure on the surface of the transport material, and although the surface treatment can be better combined with the perovskite surface radicals, the problem is that perovskite deposits on the surface of the activated charge transport material, and the perovskite itself has properties such asPLQEThe charge transport capability of the charge transport material is reduced to different degrees. In another method, a non-orthogonal solvent is introduced into an intermediate material as a transition material of a perovskite material and a charge transport material, the perovskite material is degraded due to the dissolution of the orthogonal solvent and the perovskite material, the charge transport capability of the transport material is degraded due to the dissolution of the perovskite solvent and the charge transport material, and the material is damaged by any solvent to different degrees, which means that different researchers and different operation methods have different performances from the target performance of the prepared device, and the results are poor device repeatability, high preparation complexity and high batch difficulty.

The invention aims to solve the technical problems that on one hand, the perovskite material and the charge transmission material are effectively matched, and the characteristics are that the interface potential barrier is low and the charge transmission capability is good; another aspect is that the charge transport material or perovskite material is mutually dissolved without the introduction of orthogonal solvents, in particular in that mutual dissolution between functional materials is avoided. The polar interface is used as a means for regulating and controlling the perovskite material and the photoelectric device, the final device performance can be influenced through two aspects, on one hand, the polar interface can combine the substrate with prominent performance, the charge transmission material and the perovskite material together, so that each functional material can exert prominent advantages to regulate and control the device performance finally; on the other hand, the crystal growth process is regulated, the perovskite appearance, the defect state density and the like are regulated, the purposes of improving or regulating the luminous performance, the photovoltaic performance, the carrier injection and the carrier transmission are achieved, and the overall performance of the device is finally regulated. The invention aims to provide a method for regulating and controlling a perovskite material and a photoelectric device based on a polar interface, which can achieve two purposes, on one hand, the interface adopts the polar material, so that the perovskite material and a charge transmission material can be effectively matched, and the introduced interface material enables the charge transmission material with excellent performance to be compatible with the perovskite material without reducing the performance; on the other hand, the growth of the perovskite is regulated by adopting a polar material at the interface, the polar interface is deposited on the perovskite or the charge transport material by adopting physical or chemical methods such as thermal evaporation, magnetron sputtering, MOCVD, ALD, spraying, printing, chemical synthesis and the like, the deposited material cannot dissolve the deposition interface, and the direct contact between the charge transport material and a perovskite material solvent is isolated, so that the process of mutually dissolving the charge transport material and the perovskite material cannot exist, and the charge transport material and the perovskite material are effectively matched to ensure the respective excellent characteristics.

Fig. 1 shows a perovskite structure of a common substrate polar interface, and perovskite is deposited on a substrate covered with the polar interface, wherein L1 is a perovskite thin film, L2 is a polar interface, and L3 is a substrate (a quartz plate is used as a substrate material for description below).

The quartz wafer substrate L3 was 12mm by 12mm in size and the quartz wafer was ultrasonically cleaned for 15 minutes using 7 steps of deionized water, acetone, isopropyl alcohol, deionized water, isopropyl alcohol before use. The cleaned quartz wafer was placed in a UV-Ozone cleaning machine for 15 minutes Ozone cleaning, and then the quartz wafer substrate was transferred to a glove box filled with high purity nitrogen and transferred to a vacuum coater for polar interface evaporation experiments.

The polar interface L _2 is NiO and MoO respectively₃、ZnO、MgO、Li₂CO₃、Na₂CO₃、LiF、CaF₂NaF, KF, CsF, MgO (comparative evaporation experiments of these materials were performed in the specific examples and are all listed here), and the comparative quartz plate substrate did not evaporate polar interfaces. The pressure of vacuum evaporation is 5 x10^-4Pa, the evaporation rate is measured by a quartz crystal oscillation piece, the evaporation rate is 0.01nm/s, the evaporation thickness of the polar interface is 1nm, and the quartz piece evaporated with the polar interface is transferred to a glove box filled with high-purity nitrogen to spin-coat the perovskite thin film.

The perovskite film L1 component is halide perovskite, and the perovskite precursor solution is PEA_nCsPb_nBr_3n+1Consisting of 110mg of PbBr₂(lead bromide), 64mg CsBr (cesium bromide) and 24mg PEABr (2-phenethyl ammonium bromide) were dissolved in a 1mL DMSO (dimethyl sulfoxide) solution at a molar ratio of 1:1:0.4, and the solution was stirred on a 60 ℃ hot plate for 1 hour at a concentration of 0.3 mol/L. When the perovskite is coated in a spin mode, a quartz plate coated with a polar interface in a vapor deposition mode is placed on a vacuum spin coating machine, a 100uL liquid transfer gun is used for sucking 30uL of perovskite precursor solution, the perovskite precursor solution is dripped onto the quartz plate coated with the polar interface in a vapor deposition mode, the vacuum spin coating machine carries out spin coating for 60s at the rotating speed of 3000 rpm/s, then the quartz plate coated with the perovskite in a spin coating mode is placed on a hot table and is annealed for 10min at the temperature of 60 ℃, and the perovskite luminescent film with the thickness of 35 nm is obtained.

The final perovskite thin film L1, the polar interface L2, and the substrate L3 constitute a light emitting device, but this structure is a non-conductive substrate.

FIG. 2 is a polar interface perovskite photovoltaic device structure with an ITO conductive substrate

The preparation method comprises the following steps of preparing a quartz plate without Indium Tin Oxide (ITO) as a substrate selected by the perovskite light-emitting device based on the polar interface, preparing a quartz plate with ITO as a substrate selected by the perovskite photoelectric device based on the polar interface, and preparing the two device structures according to the following procedures:

firstly, preparing a perovskite light-emitting device based on a polar interface.

The substrate selected by the perovskite light-emitting device based on the polar interface is a quartz plate substrate L3 without ITO (indium tin oxide) L6, and the preparation process of the device is as follows:

step one, cleaning the non-conductive substrate L3: the L3 component of the substrate quartz plate which is not conductive is SiO₂12mm by 12mm in size and 1mm in thickness. Before use, a non-conductive substrate L3 needs to be pretreated, ultrasonic cleaning is carried out for 15 minutes by using seven steps of deionized water, acetone, isopropanol, deionized water and isopropanol, and then the substrate is put into a UV-Ozone cleaning machine for 15 minutes of Ozone cleaning.

Step two, evaporating a polar interface material L2: the cleaned non-conductive substrate L3 was placed in a glass petri dish and the glass petri dish was transferred through a transition bin of a glove box into a nitrogen glove box with a vacuum coater. The door of the vacuum coater in the glove box was opened, and the nonconductive substrate L3 was taken out of the glass petri dish and placed on the evaporation substrate table in the vacuum coater, and the position of the evaporation substrate table was adjusted, and the shutter below the substrate table was closed.

The polar interface material L2 was transferred to a vacuum coater, placed in a thermal evaporation crucible, the position of the thermal evaporation crucible was adjusted, and the door of the vacuum coater was closed, aligning with the evaporation substrate table on which the nonconductive substrate L3 was placed. Since the polar interface material is easily affected by moisture, oxygen and other gases in the atmosphere, resulting in reduced purity and reduced performance, the polar interface material L2 was stored in a glove box filled with high purity nitrogen and, in use, the polar interface material L2 was transferred into the vacuum coater.

The baffle below the substrate table is used for preventing the polar interface material from being directly evaporated on the non-conductive substrate L3, and because the evaporation rate and the material purity of the material greatly affect the prepared polar interface film L2 in the evaporation process, the baffle below the substrate table can be opened only after the detection rate of the quartz crystal oscillating piece in the vacuum coating machine is stable, and the polar interface material L2 with stable evaporation rate can be uniformly evaporated on the non-conductive substrate L3.

After a mechanical pump and a molecular pump connected with a vacuum coating machine are started, the air pressure for waiting vacuum evaporation is reduced to 5 x10^-4Pa, the power supply of the thermal evaporation crucible is turned on, the power supply of the thermal evaporation crucible gradually heats the thermal evaporation crucible, the phenomenon that the heat loaded on the thermal evaporation crucible is too fast to cause the splashing of the polar interface material L2 is avoided, the thermal evaporation crucible is gradually heated to help form the evaporation rate of the polar interface material L2 which is uniformly evaporated, and therefore the thermal evaporation crucible needs to be gradually heated.

The evaporation rate of the polar interface material L2 detected by the quartz crystal oscillation piece is displayed by the film thickness meter, after the evaporation rate of the polar interface material L2 displayed by the film thickness meter is stable, the evaporation rate is stable at 0.01nm/s, a baffle below a base plate table in a vacuum coating machine is started, the polar interface material L2 with uniform evaporation rate can be uniformly evaporated on the non-conductive substrate L3, and the evaporation thickness of the polar interface is 1 nm.

After the polar interface material L2 is evaporated, a baffle plate below a base plate table in the vacuum coating machine is closed, a molecular pump and a mechanical pump which are connected with the vacuum coating machine are closed, then the air pressure in the vacuum coating machine is waited to be restored to the atmospheric pressure, a bin gate of the vacuum coating machine is opened, and the non-conductive substrate L3 which is evaporated with the polar interface material L2 is taken out from the base plate table. It was then placed into a glass petri dish, which was transferred through a transfer bin to a glove box equipped with a vacuum spin coater, followed by spin coating of the halide perovskite thin film L1.

Step three, spin coating halide perovskite L1: and transferring the non-conductive substrate L3 evaporated with the polar interface material L2 to a glove box with a vacuum spin-coating machine through a glass culture dish to spin-coat a halide perovskite thin film, putting the substrate evaporated with the polar interface on the vacuum spin-coating machine during the spin-coating of perovskite, sucking a perovskite precursor solution by using a liquid transfer gun, dripping the perovskite precursor solution on the substrate evaporated with the polar interface, spin-coating the substrate with the vacuum spin-coating machine at the rotating speed of 3000 rpm/s for 60s, and then putting the substrate subjected to the spin-coating of perovskite on a hot table to perform 60 ℃ annealing for 10min to obtain the perovskite thin film device.

Finally, a halide perovskite luminescent device based on a polar interface is formed, the excitation light higher than the luminescent energy of the halide perovskite is used for exciting the halide perovskite luminescent film, the halide perovskite can emit fluorescence, and the method can be used for preparing the fluorescent film based on the flexible substrate.

Secondly, preparing the perovskite photoelectric device based on the polar interface.

The substrate selected by the perovskite photoelectric device based on the polar interface is a quartz plate with ITO (indium tin oxide) L6, and the preparation process leaves:

step one, preparing a conductive substrate with ITO (indium tin oxide) L6: the conductive substrate is composed of ITO (indium tin oxide) L6 and quartz plate substrate L3, and the quartz plate is made of SiO₂12mm by 12mm in size and 1mm in thickness. ITO raw materials can be sputtered onto a quartz plate through a magnetron sputtering technology, the thickness of the ITO is 185nm, when ITO (indium tin oxide) L6 is sputtered, a quartz plate substrate L3 is placed on a substrate table with a mask plate, the mask plate can be used for partially shielding the quartz plate substrate L3, the exposed part can be sputtered with the ITO materials, the unexposed part cannot be sputtered with the ITO materials, the shape of a rectangular ITO (indium tin oxide) L6 with the size of 8 mm and 12mm is centrally sputtered onto the quartz plate substrate L3 through the mask plate, each side is vacant by 2mm, and the vacant positions are not covered by the ITO.

Step two, cleaning treatment of the conductive substrate: the conductive substrate is pretreated, ultrasonic cleaning is carried out for 15 minutes by using seven steps of deionized water, acetone, isopropanol, deionized water and isopropanol, and then the conductive substrate is placed in a UV-Ozone cleaning machine for Ozone cleaning for 15 minutes.

Step three, preparing a charge transport material L7 film: the cleaned conductive substrate is placed into a glass culture dish, the glass culture dish is conveyed into a nitrogen glove box through a transition bin of the glove box, and then the conductive substrate is placed on a vacuum spin coating machine in the nitrogen glove box. The charge transport material L7 is dissolved in a solvent, 30uL of charge transport material solution is sucked by a 100uL liquid-moving gun and evenly coated on a conductive substrate, the charge transport material L7 can completely coat ITO (indium tin oxide) L6, a button of a vacuum spin coater is started to spin at 3000rpm for 60s to form a film of the charge transport material L7, after the spin coating of the charge transport material L7 film is completed, the conductive substrate covered with the charge transport material L7 is placed on a hot bench to be annealed at a high temperature of 120 ℃ for 10min, and finally the charge transport material film L7 covered with ITO (indium tin oxide) L6 is formed on the conductive substrate.

Step four, evaporating a polar interface material L2: opening a bin gate of a vacuum coating machine in a glove box, placing a conductive substrate which is taken down from a hot table and is provided with a charge transmission material L7 into a glass culture dish, conveying the conductive substrate into the glove box with the vacuum coating machine through a transition bin, taking out the conductive substrate which is provided with the charge transmission material L7, placing the conductive substrate on an evaporation substrate table in the vacuum coating machine, adjusting the position of the evaporation substrate table, and closing a baffle below the substrate table.

The polar interface material L2 was also transferred to a vacuum coater, placed in a thermal evaporation crucible, the position of the thermal evaporation crucible was adjusted, and the door of the vacuum coater was closed, aligning the evaporation substrate table on which the conductive substrate of the charge transport material L7 was placed. Since polar interface materials are susceptible to atmospheric moisture, oxygen and other gases, resulting in reduced purity and reduced performance, they are stored in a glove box filled with high purity nitrogen and transported into the vacuum coater during use.

The baffle below the substrate table is used for preventing the polar interface material L2 from being directly evaporated on the conductive substrate provided with the charge transport material L7, and because the evaporation rate and the material purity of the material have great influence on the prepared polar interface material L2 in the evaporation process, the baffle below the substrate table can be opened only after the detection rate of the quartz crystal oscillating piece in the vacuum coating machine is stable, and the polar interface material L2 with stable evaporation rate can be uniformly evaporated on the conductive substrate covered with the charge transport material L7.

Vacuum coating for open connectionAfter the mechanical pump and molecular pump of the machine, the pressure of the vacuum vapor deposition is reduced to 5 x10^-4Pa, the power supply of the thermal evaporation crucible is turned on, the power supply of the thermal evaporation crucible gradually heats the thermal evaporation crucible, the phenomenon that the heat loaded on the thermal evaporation crucible is too fast to cause the splashing of the polar interface material L2 is avoided, the thermal evaporation crucible is gradually heated to help form the evaporation rate of the polar interface material L2 which is uniformly evaporated, and therefore the thermal evaporation crucible needs to be gradually heated.

The evaporation rate of the polar interface material L2 detected by the quartz crystal oscillation piece is displayed by the film thickness meter, after the evaporation rate of the polar interface material L2 displayed by the film thickness meter is stable, the evaporation rate is stable at 0.01nm/s, a baffle below a base plate table in a vacuum coating machine is started, the polar interface material L2 with uniform evaporation rate can be uniformly deposited on a conductive substrate covered with a charge transmission material L7, the evaporation thickness of the polar interface is 1nm, and a polar interface material film L2 is finally formed.

After the polar interface material L2 is evaporated, a baffle plate below a base plate table in the vacuum coating machine is closed, a molecular pump and a mechanical pump which are connected with the vacuum coating machine are closed, then the air pressure in the vacuum coating machine is recovered to the atmospheric pressure, a bin gate of the vacuum coating machine is opened, the conductive substrate which is evaporated with the polar interface material L2 and covered with the charge transmission material L7 is taken out from the base plate table. It was then placed into a glass petri dish and the petri dish was transferred through a transition bin to a glove box with a vacuum spin coater.

Step five, spin coating a halide perovskite thin film L1: the perovskite thin film is halide perovskite which is composed of different components and can form precursor solutions with different characteristics by dissolving in polar solvent. During spin coating, the conductive substrate which is evaporated with the polar interface material L2 and covered with the charge transport material L7 is placed on a vacuum spin coating machine, a 100uL liquid transfer gun is used for sucking 30uL halide perovskite precursor solution to be uniformly coated on the conductive substrate which is evaporated with the polar interface material L2 and covered with the charge transport material L7, a button of the vacuum spin coating machine is started to spin coat for 60s at 5000rpm to form a thin film of the halide perovskite L1, and the conductive substrate which is covered with the halide perovskite L1, evaporated with the polar interface material L2 and covered with the charge transport material L7 is placed on a hot table to be subjected to high-temperature annealing at 90 ℃ for 10min, so that the uniform halide perovskite thin film L1 is finally formed.

Step six, evaporating a cathode charge transport material L5: putting the annealed conductive substrate covered with halide perovskite L1, evaporated polar interface material L2 and charge transfer material L7 into a glass culture dish, conveying the conductive substrate into a glove box with a vacuum coating machine through a transition bin, taking the conductive substrate out of the glass culture dish, putting the conductive substrate on an evaporation substrate table in the vacuum coating machine, adjusting the position of the evaporation substrate table, and closing a baffle below the substrate table.

The charge transport material L5 was transferred to a vacuum coater and placed in a thermal evaporation crucible, the position of the thermal evaporation crucible was adjusted to align the electrically conductive substrate covered with halide perovskite L1, evaporated with polar interface material L2, covered with charge transport material L7, and the door of the vacuum coater was closed. Since the charge transport material is easily affected by moisture, oxygen and other gases in the atmosphere, resulting in a decrease in purity and a decrease in performance, the charge transport material L5 was stored in a glove box filled with high-purity nitrogen and transferred into a vacuum coater during use.

After a mechanical pump and a molecular pump connected with a vacuum coating machine are started, the air pressure for waiting vacuum evaporation is reduced to 5 x10^-4Pa, the power supply of the thermal evaporation crucible is turned on, the power supply of the thermal evaporation crucible gradually heats the thermal evaporation crucible, the phenomenon that the heat loaded on the thermal evaporation crucible is too fast to cause the splashing of the charge transport material L5 is avoided, the gradual heating of the thermal evaporation crucible is helpful for forming the evaporation rate of the charge transport material L5 which is uniformly evaporated, and therefore the thermal evaporation crucible needs to be gradually heated.

The evaporation rate of the charge transport material L5 detected by the quartz crystal oscillator piece is displayed by a film thickness meter, after the evaporation rate of the charge transport material L5 displayed by the film thickness meter is stabilized, the evaporation rate is stabilized at 0.05nm/s, a baffle plate below a base plate table in a vacuum coating machine is opened, the charge transport material L5 with uniform evaporation rate can be uniformly deposited on a conductive substrate covered with halide perovskite L1, a polar interface material L2 and a charge transport material L7, the evaporation thickness of the charge transport material L5 is 40nm, and finally a charge transport material L5 thin film is formed.

Step seven, evaporating an electrode L4: after the charge transport material L5 is evaporated, the charge transport material is placed on a metal mask plate in a vacuum coating machine, and a halide perovskite thin film with the area of 5.25mm can be formed through two rows of rectangular shapes (1.5 mm x 3.5 mm) L4 of the mask plate²The electrode material is composed of different kinds of metals and fluorides.

The evaporation rate of the electrode L4 detected by the quartz crystal oscillator piece is displayed by a film thickness meter, after the evaporation rate of the electrode L4 displayed by the film thickness meter is stabilized, the evaporation rate is stabilized at 0.2nm/s, a baffle plate below a base plate table in a vacuum coating machine is opened, the electrode L4 with uniform evaporation rate can be uniformly deposited on a conductive substrate covered with a charge transport material L5, a halide perovskite L1, a polarity interface material L2 and a charge transport material L7, the evaporation thickness of the electrode L4 is 100nm, and finally an electrode L4 film is formed.

Finally, a halide perovskite photoelectric device based on a polar interface is formed, and the device can finally work under current drive by loading positive and negative voltages on ITO (indium tin oxide) L6 and an electrode L4.

The interface of the polar material is formed by adopting different methods, such as physical or chemical methods of thermal evaporation, magnetron sputtering, MOCVD, ALD, spraying, printing, chemical synthesis and the like, the typical deposition thickness range is 0.1 nm-1000 nm, and the functional requirements of the current photoelectric device can be met for the devices with most of the current functional materials in the nanometer level.

Compared with direct deposition onto quartz or glass (SiO)₂) The perovskite thin film on the substrates such as ITO, Si, FTO, PTFE and the like has more defects, poor crystal orientation, less defects deposited on a polar interface and high film coverage, can realize effective transition of the substrate or a transmission material and the perovskite, and the polar interface plays a role in regulating and controlling the crystal growth process, can regulate and control the crystal growth appearance, the crystal quality and the luminous efficiency.

For combinations of elements of different groups of the periodic TableThe material interface formed by the material interface is a polar material with the difference of the electronegativity of the material between 0 and 2, and is a strong polar material with the difference of the electronegativity of the material more than 2, and the material interface can play a role in regulating and controlling the properties of the perovskite material and the photoelectric device, such as regulating and controlling the growth size of perovskite crystals, the light-emitting wavelength and the photoinduced external quantum efficiencyPLQEOpen circuit voltage of solar cellV _OCShort-circuit currentJ _SCPower conversion efficiencyPCEAnd the like. The material boundary being formed by a plurality of compounds, e.g. polar material boundaries which form compounds during different periods, e.g. ZrO₂、V₂O₅、Al₂O₃、NiO、MoO₃、ZnO、MgO、NiO、SnO₂And the like metal oxide material interface. Interfaces of polar materials between different groups that can form compounds, e.g. Li₂CO₃、Na₂CO₃、 Cs₂CO₃And the like carbonate metal compound material. Interfaces of strongly polar materials between different groups, which can form compounds, e.g. LiF, NaF, KF, RbF, CsF, MgF₂、CaF₂Etc. metal fluoride material interface. Including other material interfaces that may interact with the perovskite material, such as PTFE, piezoelectric films, piezoelectric ceramics, and the like.

The polarity of the material interface can be changed by regulation, for example, the polar interface is regulated to be a non-polar interface, or the non-polar interface is regulated to be a polar interface, and finally the final performance of the device is regulated by changing the polarity mode of the material interface.

The polar interface can regulate and control the luminescent characteristic of the perovskite material, reduce the fluorescent quenching of the substrate or the transmission material to the perovskite thin film, and regulate and control the fluorescent life of the thin film and the photoinduced external quantum efficiency PLQE.

The polar interface can enable the perovskite material and the charge transmission material to be effectively matched, the interface of the photoelectric device prepared based on the polar interface can regulate and control injection potential barriers among all functional materials, regulate and control or increase the charge transmission capability, no matter in a PN type material or a PIN type material, the flow of carriers can not be limited, and the carrier transmission characteristic can be improved or regulated and controlled.

The introduction of the polar interface can balance the transmission rate of electron holes, regulate and control the performance of the perovskite optoelectronic device, such as reducing the turn-on voltage of a light-emitting diodeV _TImproving the luminous brightness and the filling factor of the solar cellFFOpen circuit voltageV _OCShort-circuit currentJ _SCPower conversion efficiencyPCEAnd the like, and the detection sensitivity of the photoelectric detector is increased.

The polar material interface can be applied to various photoelectric devices, including solar cells, light emitting diodes, detectors, fluorescent films, fluorescent powder, semiconductor transistors, lasers and other photoelectric devices and materials.

Principle of operation

At present, the perovskite material and the photoelectric device still have defects in the aspects of photoelectric property and stability, because the perovskite belongs to a polar ion crystal, and according to the similar compatibility principle, if the phenomenon of lattice mismatching exists, various problems can be caused. The main reasons are shown in two aspects, on one hand, the substrate with prominent performance, the charge transport material and the perovskite material cannot be perfectly matched, and the performance of the prepared perovskite photoelectric device is limited, for example, for the photoelectric device prepared by a solution method, the charge transport material and the perovskite material have an interfacial mutual dissolution phenomenon, so that the interface is not perfect, and the performance of each functional material is influenced; on the other hand, the perovskite material has problems, which are represented by poor crystal growth quality and more crystal boundary and interface defects, and finally limits the performance of the perovskite material and the photoelectric device. Based on these two problems, it is necessary to consider not introducing new components to destroy the original perovskite components when optimizing perovskite materials and optoelectronic devices, and to make the perovskite materials and the charge transport materials effectively matched. According to the invention, the polar interface is used as a means for regulating the perovskite material and the photoelectric device, the final device performance can be influenced through two aspects, on one hand, the polar interface can combine the substrate with prominent performance, the charge transmission material and the perovskite material together, so that each functional material plays a role in regulating the device performance finally; on the other hand, the crystal growth process is regulated, the aims of improving or regulating the luminous performance, the photovoltaic performance, the carrier injection and the carrier transmission are achieved by regulating the perovskite appearance, the defect state density and the like, and the overall performance of the device is optimized or regulated finally.

For example, a strong polar material is used as an interface material of a perovskite device, and since the perovskite is a strong polar material and can be well matched with the polar material, different polar materials are selected as the interface material and are introduced between the charge transport material and the perovskite material for lattice matching. By adopting the ultrathin polar material to deposit on the polymer hole transport material, the perovskite can be ensured to effectively grow on the polymer charge transport material covered with the polar interface, and the strong polar material can increase the growth quality of perovskite crystals, which is expressed by prolonging the service life of current carriers of the perovskite thin film, increasing the external quantum efficiency PLQE of the perovskite thin film and further increasing the stability of the thin film and the performance of a device based on the perovskite.

The polar interface is deposited on the perovskite or charge transmission material by adopting physical or chemical methods such as thermal evaporation, magnetron sputtering, MOCVD, ALD, spraying, printing, chemical synthesis and the like, the typical deposition thickness range is 0.1 nm-1000 nm, and the functional requirements of most of the current photoelectric devices can be met for the devices with most of the current functional materials in the nanometer level. Compared to direct deposition to SiO₂The perovskite thin film on the substrate has many defects and poor crystal orientation, the polar interface plays a role in regulating and controlling crystal growth, the polar interface is matched with the polar perovskite to increase the quality of the thin film, the growth size of the crystal perovskite can be increased, the surface defect and the bulk defect density can be reduced, the spectral characteristics and components of the thin film can not be influenced, the perovskite thin film can effectively inhibit non-radiative recombination and increase radiative recombination, the fluorescence life of a current carrier of the thin film is further prolonged, and higher photoinduced external quantum efficiency is realized. The polar interface can reduce the fluorescence quenching of the substrate or the transmission material to the perovskite thin film due to the isolation of the charge transmission material and the perovskite material.

Polar interfaceThe perovskite material and the charge transport material can be effectively matched, and the interface of the photoelectric device prepared based on the polar interface can regulate and control injection potential barrier between the charge transport material and the perovskite material, and regulate or increase charge transport capability. The polar interface acts as a very thin tunneling material, neither in PN-type materials nor PIN-type materials, and does not restrict the flow of carriers. If a thicker polar interface material is used, the bipolar characteristic of the interface material can be utilized to partially block holes or electrons to realize charge balance in the device, realize charge transmission regulation to balance the transmission rate of electron holes, and improve the performance of the perovskite optoelectronic device, such as reducing the turn-on voltage of a light-emitting diodeV _TImproving the filling factor of the solar cellFFShort-circuit currentJ _SCOpen circuit voltageV _OCPower conversion efficiencyPCEAnd increasing the detection sensitivity of the photoelectric detector and other parameters.

According to one aspect of the invention, a method for optimizing a perovskite thin film and a light-emitting device based on a polar interface is provided, which specifically describes a method for introducing the polar interface into a substrate or between a charge transport material and the perovskite material by taking the light-emitting thin film and a light-emitting diode as examples, and aspects of regulating or optimizing the performance of the perovskite thin film and the perovskite device after the introduction of the polar interface is represented by a test instrument.

1. The working principle of the perovskite thin film can be regulated or optimized by the polar interface

Perovskite belongs to polar ion crystal, generally can adopt methods such as solution method, thermal deposition method to synthesize, in luminescent film or photoelectric device based on perovskite, perovskite is by many nm or micron size perovskite block forms compact film, and these blocks are by many nm size perovskite crystal formation, in perovskite form crystal block process by raw materials, external environment can have very big influence to the crystallization. When perovskite is combined with a substrate and a charge transport material, if the phenomenon of lattice mismatch exists, various problems are caused. The main reasons are shown in two aspects, on one hand, the substrate with prominent performance, the charge transport material and the perovskite material cannot be perfectly matched, and the performance of the prepared perovskite photoelectric device is limited, for example, for the photoelectric device prepared by a solution method, the charge transport material and the perovskite material have an interfacial mutual dissolution phenomenon, so that the interface is not perfect, and the performance of each functional material is influenced; on the other hand, the perovskite material has problems, which are represented by poor crystal growth quality and more crystal boundary and interface defects, and finally limit the performance of the perovskite material and the photoelectric device.

The invention adopts the polar material as the interface material of the perovskite film and the photoelectric device, the main reason is to regulate or optimize the performance of the perovskite film or the photoelectric device through the polar interface, the perovskite has the main structural formula of ABX₃Where a is an organic or inorganic cation, B is a metal cation, and X is a halide anion, the combination of the different materials A, B, X results in the perovskite crystal also being a polar material. According to a similar compatibility principle, perovskites can be well matched with polar materials. Naturally, the difference of electronegativity of elements contained in different materials can cause the formed materials to have different polarities, and in chemistry, the polarity refers to the phenomenon that centers of positive and negative charges are not overlapped in a covalent bond or a covalent molecule due to the nonuniformity of charge distribution. If the charge distribution is not uniform, the bond or molecule appears polar; if the charge distribution is very uniform, it appears non-polar. Some physical properties of a substance (e.g., solubility, melting point, etc.) are related to the polarity of the molecule. For polar covalent molecules, it is indicated that the internal charge distribution is not uniform or the positive and negative charge centers do not coincide, the polarity of the molecule depends on the polarity of each bond in the molecule and their arrangement, and the polarity affects the movement of the positive and negative charge centers of the materials adjacent to the polarity.

The difference in polarity of materials affects the surface energy of the materials, which is a measure of the breakdown of intermolecular chemical bonds when forming a substance surface. In solid physics, surface atoms have more energy than atoms inside a substance, and therefore, according to the principle of energy minimization, atoms tend spontaneously to the inside of a substance rather than to the surface. Another definition of surface energy is the excess energy at the surface of a material relative to the interior of the material. Breaking a solid material into small pieces requires breaking chemical bonds within it and therefore consumes energy. If this decomposition process is reversible, the energy required to decompose the material into small pieces is equal to the energy added to the surface of the small pieces, i.e., the surface energy is increased. In fact, however, only the surface that has just been formed in a vacuum complies with the law of conservation of energy. Because the newly formed surfaces are very unstable, they have a reduced surface energy through surface atom recombination and interaction with each other, or adsorption to other molecules or atoms in the surroundings. In the material, the bond energy of the atoms of the surface layer facing to the outside is not compensated, so that the surface particles have extra potential energy than the particles in the body, the internal energy changes due to the change of the surface area of the body, the value of the surface energy per unit area is the same as the surface tension, but the values and the surface tension are different in physical meaning, but the surface energy can be indirectly researched through the surface tension.

Due to the fact that the surface energy of a part of substrates and charge transport materials is low, the surface energy is reduced due to the fact that nonpolar organic groups exist on the surfaces of some charge transport materials, the perovskite materials are not easily spread, the perovskite materials are not compact in growth, low in coverage rate and large in surface defect and body defect density, molecular adsorption force is further reduced, and the phenomena that the perovskite materials are easy to fall off, bloom and are not covered locally are caused. The polar interface is introduced to the surfaces of the substrate with low surface energy and the charge transport material, so that the surface of the substrate and the charge transport material can be modified, the perovskite material can be matched with the perovskite material properly, the contact angles of the perovskite material on the substrate and the charge transport material can be reduced, the wettability of the perovskite material on the surfaces of the substrate and the charge transport material is increased, the perovskite material is combined with the substrate and the charge transport material more firmly and is not easy to peel off, and the perovskite material grows more densely, the coverage rate is increased, and the surface defect density and the bulk defect density are reduced.

The density, the surface coverage rate, the surface defect density and the bulk defect density of the perovskite growth can be regulated and controlled through interface materials with different polarities, and meanwhile, the perovskite on the polar interface can effectively grow on a polymer charge transport material with poor wettability. The growth direction of the perovskite material can be induced by adopting the strong-polarity interface material, so that the growth directivity and compactness of the perovskite crystal material are increased, the carrier life of the perovskite film is prolonged, the external quantum efficiency PLQE of the perovskite film is increased, and the stability of the perovskite film and the performance of the perovskite-based photoelectric device are further increased.

The polar interface can enable the perovskite material to be effectively matched with the charge transport material, and the interface of the photoelectric device prepared based on the polar interface can regulate and control injection potential barriers between the charge transport material and the perovskite material, and regulate or increase the charge transport capability. The polar interface acts as a very thin tunneling material, neither in PN-type materials nor PIN-type materials, and does not restrict the flow of carriers. If a thicker polar interface material is used, the bipolar characteristic of the interface material can be utilized to partially block holes or electrons to realize charge balance in the device, realize charge transmission regulation to balance the transmission rate of electron holes, and improve the performance of the perovskite optoelectronic device, such as reducing the turn-on voltage of a light-emitting diodeV _TAnd improveFill factor for solar cellsFFShort-circuit currentJ _SCOpen circuit voltageV _OCPower conversion efficiencyPCEAnd increasing the detection sensitivity of the photoelectric detector and other parameters.

2. Preparation method and characterization of hydrophilicity experiment after introduction of polar interface

FIG. 3 is a flow chart of the preparation of hydrophilic experiments with polar interfaces. The polar interface is deposited on a quartz plate without conductive glass ITO, the size of the quartz plate is 12mm x 12mm, and the quartz plate is subjected to ultrasonic cleaning for 15 minutes by using steps of deionized water, acetone, isopropanol, deionized water and isopropanol before use. And (3) putting the cleaned quartz plate into a UV-Ozone cleaning machine for Ozone cleaning for 15 minutes, then transferring the quartz plate into a glove box filled with high-purity nitrogen, selecting a polar interface material to be evaporated, and then transferring into a vacuum coating machine for polar interface evaporation until the evaporation is finished. The pressure of vacuum evaporation is 5 x10^-4Pa, the evaporation rate is measured by a quartz crystal oscillation plate, the evaporation rate is 0.01nm/s, and the evaporation thickness of LiF on the polar interface is 1 nm.

Fig. 4 shows a comparison of the hydrophilicity wetting experiment before and after the interface is added, and the test solution is DMSO, it can be seen that the wettability of the substrate after the interface is added is enhanced, which indicates that the solvent is more easily spread after the interface is added, and the perovskite is dissolved in the DMSO solvent, so that the perovskite is more tightly combined with the substrate on the polar interface.

3. Comparative characterization of charge transport materials by surface treatment with polar interfaces and plasma, respectively

FIG. 5 is a flow chart of surface treatment using a polar interface and plasma, respectively. Because the surface energy of the selected charge transport material is lower, the name of the charge transport material is poly (9, 9-dioctyl fluorene-alt-N- (4-sec-butylphenyl) -diphenylamine) (TFB for short), the perovskite material is not easy to spread, so that the film is not completely covered, and generally plasma is adopted for surface treatment to increase the surface energy, so that the perovskite coating is more complete. The charge transport material TFB was prepared on quartz glass 12mm by 12mm in size, which was ultrasonically cleaned with 5 steps of deionized water, acetone, isopropanol, deionized water, isopropanol for 15 minutes before use. The quartz glass after cleaning was placed in a UV-Ozone cleaning machine for Ozone cleaning for 15 minutes, and then the quartz glass was transferred to a glove box filled with high-purity nitrogen, and the quartz glass was placed on a vacuum spin coater for spin coating of a charge transport material. The charge transport material TFB is dissolved in chlorobenzene solution (CB for short), the concentration is 6mg/ml, when the charge transport material TFB is coated, a liquid-moving gun with the dosage of 100uL is used for sucking 30uL of the charge transport solution to coat the ITO conductive glass, a vacuum spin-coating machine is started to spin-coat for 60s at the rotating speed of 3000 rpm/s, the ITO conductive glass after the charge transport material is spin-coated is placed on a hot table to be annealed at 120 ℃ for 10min, and the flat charge transport material TFB film with the thickness of 10nm is obtained.

And then transferring the quartz glass coated with the charge transport material to a vacuum coating machine for polar interface LiF evaporation. The pressure of vacuum evaporation is 5 x10^-4Pa, the evaporation rate is measured by a quartz crystal oscillation plate, the evaporation rate is 0.01nm/s, and the evaporation thickness of LiF on the polar interface is 1nm until the evaporation is finished.

The charge transport material substrate as a comparative experiment was subjected to surface treatment directly with a plasma cleaner for a period of 5 s.

Fig. 6 is an SEM image showing a surface morphology of a charge transport material surface-treated with a LiF polar interface and Plasma, and since TFB and its derivatives are hole transport materials with relatively outstanding transport properties, but a perovskite using DMSO as a solvent is incompatible with TFB, and the perovskite cannot be directly deposited on a functional material based on TFB and its derivatives, a general method is to perform surface treatment with a Plasma surface cleaner and a UV-Ozone surface cleaner, but the surface morphology is destroyed after the surface treatment, and relatively many holes are formed, which increases an injection barrier when contacting the perovskite or forms a surface defect or a bulk defect at an interface position, thereby causing a performance degradation of a device. The TFB hole transport material processed by LiF interface is more compact, the possibility of electric leakage of the device is reduced, and the performance of the charge transport material is not changed. Meanwhile, a polar interface represented by LiF is used as a tunneling layer, so that the injection barrier of charges can be reduced, the charge transport material with excellent performance can be friendly-matched with the perovskite material, and the overall performance of the device is improved.

4. SEM test comparison and characterization of perovskite on interfaces with different polarities

Fig. 7 is a view SEM flow chart of spin-on perovskite luminescent thin films. The luminescent film is deposited on a quartz plate without conductive glass ITO, the size of the quartz plate is 12mm x 12mm, and the quartz plate is ultrasonically cleaned for 15 minutes by using the steps of deionized water, acetone, isopropanol, deionized water and isopropanol before use. Putting the cleaned quartz wafer into a UV-Ozone cleaning machine for Ozone cleaning for 15 minutes, then transferring the quartz wafer into a glove box filled with high-purity nitrogen, selecting a polar interface material to be evaporated, and then transferring the quartz wafer into a vacuum coating machine for carrying out polar interface respective evaporation experiments, wherein the polar interface materials are LiF and CaF respectively₂NaF, CsF, MgO, comparative Quartz glass SiO₂No evaporation experiments were performed. The pressure of vacuum evaporation is 5 x10^-4Pa, the evaporation rate is measured by a quartz crystal oscillation plate, the evaporation rate is 0.01nm/s, the evaporation thickness of the polar interface is 1nm, and the quartz plate with the evaporated polar interface is transferred to a glove box filled with high-purity nitrogen to spin-coat the perovskite material.

The perovskite precursor solution is PEA_nCsPb_nBr_3n+1Consisting of 110mg of lead bromide (PbBr)₂) 64mg of cesium bromide (CsBr) and 24mg of 2-phenethylammonium bromide (PEABr) were dissolved in 1mL of a dimethyl sulfoxide (DMSO) solution at a concentration of 0.3 mol/L, and the solution was stirred on a 60 ℃ hot plate for 1 hour. During spin coating, the quartz plate is placed on a vacuum spin coating machine, the prepared precursor perovskite solution is coated on the quartz plate coated with the polar interface by evaporation, the quartz plate is spin-coated for 60s at the rotating speed of 3000 rpm/s, the quartz glass of the perovskite material after spin coating is placed on a hot table for annealing at the temperature of 60 ℃ for 10min, and the flat perovskite material film with the thickness of 35 nm is obtained.

FIG. 8 shows the SEM morphology of the perovskite film formed on different interfaces, the substrate used is a quartz piece SiO₂At the very strong pointSexual interface LiF, CaF₂After perovskite is deposited on NaF and CsF, compact thin films can be formed, which means that devices based on polar interfaces have good interfaces, the probability of electric leakage is reduced, and SiO is formed on a quartz plate₂And the perovskite deposited on the MgO of the weak polarity interface has more holes, and can cause the electric leakage phenomenon in a formed device, so the strong polarity interface can play a role in regulating and controlling the growth of the perovskite, play a role in inducing the crystallization of the perovskite and further change the growth morphology of the perovskite.

5. Wavelet test comparison and characterization of perovskite on interfaces with different polarities

FIG. 9 is a flow chart of a spin-coating perovskite luminescent thin film test wavelet. The luminescent film is deposited on a quartz plate without conductive glass ITO, the size of the quartz plate is 12mm x 12mm, and the quartz plate is ultrasonically cleaned for 15 minutes by using the steps of deionized water, acetone, isopropanol, deionized water and isopropanol before use. Putting the cleaned quartz wafer into a UV-Ozone cleaning machine for Ozone cleaning for 15 minutes, then transferring the quartz wafer into a glove box filled with high-purity nitrogen, selecting a polar interface material to be evaporated, and then transferring the quartz wafer into a vacuum coating machine for carrying out polar interface respective evaporation experiments, wherein the polar interface material is Cs₂CO₃、LiF、CaF₂NaF, KF, CsF, comparative Quartz glass SiO₂The vapor deposition experiment was not performed (named None). The pressure of vacuum evaporation is 5 x10^-4Pa, the evaporation rate is measured by a quartz crystal oscillation plate, the evaporation rate is 0.01nm/s, the evaporation thickness of the polar interface is 1nm, and the quartz plate with the evaporated polar interface is transferred to a glove box filled with high-purity nitrogen to spin-coat the perovskite material.

The perovskite precursor solution is PEA_nCsPb_nBr_3n+1Consisting of 110mg of lead bromide (PbBr)₂) 64mg of cesium bromide (CsBr) and 24mg of 2-phenethylammonium bromide (PEABr) were dissolved in 1mL of a dimethyl sulfoxide (DMSO) solution at a concentration of 0.3 mol/L, and the solution was stirred on a 60 ℃ hot plate for 1 hour. During spin coating, the quartz plate is put on a vacuum spin coating machine, and the prepared precursor perovskite solution is coated on the vaporAnd spin-coating the quartz plate coated with the polar interface at 3000 rpm/s for 60s, placing the quartz glass coated with the perovskite material on a hot table, and annealing at 60 ℃ for 10min to obtain a flat perovskite material film with the thickness of 35 nm.

The spectral measurement of the luminescent film is realized by a luminance meter, a quartz plate coated with perovskite by evaporation is placed on a luminance meter test bench, the fluorescent film is excited by 365 nm ultraviolet light, the spectral detection range of the luminance meter is 380 nm-950 nm, and the luminescent range of a sample can be completely covered.

FIG. 10 shows the PL spectrum of a material grown on an interface of different polarity, with the spectroscopic measuring instrument being a luminance meter, Wavelength Wavelength on the horizontal axis in nm, and Normalized spectral intensity Normalized PL on the vertical axis. From the fact that the luminescence spectrum of the perovskite in fig. 5 is substantially unchanged, it is demonstrated that the polar interface does not change the crystalline composition of the perovskite.

6. Absorbance absorption testing procedure and characterization of perovskite on interfaces with different polarities

FIG. 11 is a flow chart of a spin-on perovskite luminescent thin film test Absorbance. The luminescent film is deposited on a quartz plate without conductive glass ITO, the size of the quartz plate is 12mm x 12mm, and the quartz plate is ultrasonically cleaned for 15 minutes by using the steps of deionized water, acetone, isopropanol, deionized water and isopropanol before use. Putting the cleaned quartz wafer into a UV-Ozone cleaning machine for Ozone cleaning for 15 minutes, then transferring the quartz wafer into a glove box filled with high-purity nitrogen, selecting a polar interface material to be evaporated, and then transferring the quartz wafer into a vacuum coating machine for carrying out polar interface respective evaporation experiments, wherein the polar interface materials are LiF and CaF respectively₂NaF, KF, CsF, SiO, Quartz glass for comparative experiments₂Non-polar interface materials. The pressure of vacuum evaporation is 5 x10^-4Pa, the evaporation rate is measured by a quartz crystal oscillation plate, the evaporation rate is 0.01nm/s, the evaporation thickness of the polar interface is 1nm, and the quartz plate with the evaporated polar interface is transferred to a glove box filled with high-purity nitrogen to spin-coat the perovskite material.

The perovskite precursor solution is PEA_nCsPb_nBr_3n+1Which is composed of110mg of lead bromide (PbBr)₂) 64mg of cesium bromide (CsBr) and 24mg of 2-phenethylammonium bromide (PEABr) were dissolved in 1mL of a dimethyl sulfoxide (DMSO) solution at a concentration of 0.3 mol/L, and the solution was stirred on a 60 ℃ hot plate for 1 hour. During spin coating, the quartz plate is placed on a vacuum spin coating machine, the prepared precursor perovskite solution is coated on the quartz plate coated with the polar interface by evaporation, the quartz plate is spin-coated for 60s at the rotating speed of 3000 rpm/s, the quartz glass of the perovskite material after spin coating is placed on a hot table for annealing at the temperature of 60 ℃ for 10min, and the flat perovskite material film with the thickness of 35 nm is obtained.

The absorption measurement of the film is realized by an ultraviolet visible spectrophotometer, a quartz plate of the evaporated perovskite is placed on a spectrophotometer test board, the excitation spectrum range is 190 nm-1100 nm, and the light-emitting range of a sample can be completely covered. The quartz plate covered with the perovskite is placed on a test rack of the ultraviolet spectrophotometer, one-step spectrum calibration is carried out by adopting a standard quartz plate before testing so as to obtain more accurate measurement, and the ultraviolet spectrophotometer can completely cover the light absorption range of a sample.

FIG. 12 shows absorption spectra of perovskite materials grown on interfaces of different polarities, the interface materials from top to bottom being LiF and CaF₂NaF, KF, CsF and SiO₂Wherein LiF, CaF₂NaF, KF, CsF denote the deposition of perovskites on a substrate covered with a corresponding polar interface material, SiO₂Indicating perovskite deposition onto a quartz substrate covered with a non-polar interface material. The absorption spectrum measuring instrument is an ultraviolet spectrophotometer, the horizontal axis is a spectrum wavelet emitted by the ultraviolet spectrophotometer, the unit is nm, and the vertical axis is an absorption coefficient Absorbance of a material detected by the ultraviolet spectrophotometer and corresponding to the current Wavelength. Fig. 6 shows that the absorption spectrum of the perovskite material has little change, which indicates that the added polar interface does not change the essential structure and composition of the luminescent thin film.

7. X-ray diffraction preparation of perovskite on interfaces of different polarity and characterization (XRD)

FIG. 13 is a flow chart of a test XRD of spin-on perovskite luminescent thin film. The luminescent film is deposited on a quartz plate without conductive glass ITO,the quartz plate was 12mm by 12mm in size and was ultrasonically cleaned with deionized water, acetone, isopropyl alcohol, deionized water, isopropyl alcohol for 15 minutes before use. Putting the cleaned quartz wafer into a UV-Ozone cleaning machine for Ozone cleaning for 15 minutes, then transferring the quartz wafer into a glove box filled with high-purity nitrogen, selecting a polar interface material to be evaporated, and then transferring the quartz wafer into a vacuum coating machine for carrying out polar interface respective evaporation experiments, wherein the polar interface material is MoO₃、ZnO、MgO、Li₂CO₃、Na₂CO₃、Cs₂CO₃、LiF、CaF₂NaF, KF and CsF. The pressure of vacuum evaporation is 5 x10^-4Pa, the evaporation rate is measured by a quartz crystal oscillation plate, the evaporation rate is 0.01nm/s, the evaporation thickness of the polar interface is 1nm, and the quartz plate with the evaporated polar interface is transferred to a glove box filled with high-purity nitrogen to spin-coat the perovskite material.

The XRD diffraction measurement adopts Bruker equipment, the measurement degree range is 10-45 degrees, the measurement stepping interval is 0.02 degrees, the measurement time is 5 degrees/min, the measurement voltage is 40kV, and the measurement current is 30 mA.

FIG. 14 shows thin film XRD of perovskites at different interfaces, with degree on the horizontal axis and relative intensity on the vertical axis. The polar interface materials from top to bottom are respectively LiF and CaF₂、NaF、KF、CsF、SiO₂And bkgd, wherein LiF, CaF₂NaF, KF, CsF denote perovskite deposition to the overlayOn a substrate with a corresponding polar interface material, SiO₂Indicating the deposition of the perovskite onto the quartz substrate without the polar interface material coating and bkgd indicating the diffraction peak of the quartz substrate without the perovskite coating. Compared to SiO deposited directly onto quartz plate₂The 100 and 200 peaks of the perovskite thin film on the substrate have enhancement tendency, but other peak types are not increased, which shows that the polar interface enhances the components of the perovskite in the peaks and plays a role in regulating and controlling the components in the perovskite thin film.

8. Photoinduced external quantum efficiency PLQE of perovskite on interfaces with different polarities and characterization

Fig. 15 is a flow chart of the photoluminescence quantum efficiency PLQE test for different interfaces. The luminescent film is deposited on a quartz plate without conductive glass ITO, the size of the quartz plate is 12mm x 12mm, and the quartz plate is ultrasonically cleaned for 15 minutes by using the steps of deionized water, acetone, isopropanol, deionized water and isopropanol before use. Putting the cleaned quartz wafer into a UV-Ozone cleaning machine for Ozone cleaning for 15 minutes, then transferring the quartz wafer into a glove box filled with high-purity nitrogen, selecting a polar interface material to be evaporated, and then transferring the quartz wafer into a vacuum coating machine for carrying out polar interface respective evaporation experiments, wherein the polar interface material is MoO₃、ZnO、MgO、Li₂CO₃、Na₂CO₃、Cs₂CO₃、LiF、CaF₂NaF, KF and CsF. The pressure of vacuum evaporation is 5 x10^-4Pa, the evaporation rate is measured by a quartz crystal oscillation plate, the evaporation rate is 0.01nm/s, the evaporation thickness of the polar interface is 1nm, and the quartz plate with the evaporated polar interface is transferred to a glove box filled with high-purity nitrogen to spin-coat the perovskite material.

The perovskite precursor solution is PEA_nCsPb_nBr_3n+1Consisting of 110mg of lead bromide (PbBr)₂) 64mg of cesium bromide (CsBr) and 24mg of 2-phenethylammonium bromide (PEABr) were dissolved in 1mL of a dimethyl sulfoxide (DMSO) solution at a concentration of 0.3 mol/L, and the solution was stirred on a 60 ℃ hot plate for 1 hour. During spin coating, the quartz plate is put on a vacuum spin coater, and the prepared precursor perovskite solution is coated on evaporation platingAnd spin-coating the quartz plate with the polar interface at 3000 rpm/s for 60s, placing the quartz glass subjected to spin-coating to obtain the perovskite material on a hot table, and annealing at 60 ℃ for 10min to obtain a flat perovskite material film with the thickness of 35 nm.

Taking the quartz plate with the perovskite being coated in a spinning mode out of a glove box to measure the photoinduced quantum efficiency PLQE, placing the quartz plate into an external integrating sphere to measure the PLQE, wherein the integrating sphere system consists of an Ocean HDX series spectrometer, a 405 nm wavelength continuous laser, a 10 cm diameter integrating sphere and a computer upper computer system, and the PLQE of the perovskite sample is measured by a three-step method.

The variation of the photoinduced external quantum efficiency PLQE of the perovskite with the electronegativity of the interfaces with different polarities is shown in FIG. 16, the electronegativity Difference in the interfaces with polarities is shown on the horizontal axis, and the photoinduced external quantum efficiency PLQE of the perovskite on the interfaces with polarities is shown on the vertical axis. Wherein SiO is₂The interface is the direct deposition of perovskite onto the quartz substrate. Wherein NiO and MoO are formed on the polar interface₃、ZnO、MgO、Li₂CO₃、Na₂CO₃The PLQE of the perovskite is reduced through the upper interface, which shows that the PLQE of the perovskite is influenced by the fluorescent quenching or light absorption process, and the influence of the polar interface on the perovskite is smaller and smaller along with the increase of the polarity, which shows that the polarity matching is required when the polar interface is utilized in the perovskite system. Wherein Cs is at the polar interface₂CO₃、LiF、CaF₂NaF, KF and CsF can increase the fluorescence of perovskite compared with SiO₂The material interface shows that the polar interface inhibits non-radiative recombination and increases radiative recombination, which shows that the strong polar interface can enable the perovskite film to realize higher light-emitting efficiency, and simultaneously shows the phenomena of sequential reduction along with the change of metal activity, which shows that the performance of the perovskite is reduced to some extent when the perovskite grows on the surfaces of different metal compounds. After the introduction of several interfaces, the fluorescence lifetime of several interfaces capable of enhancing PLQE is also increased, which shows that the interface action enables the perovskite growth quality to be better, inhibits the non-radiative recombination process, enhances the radiative recombination process, and realizes higher PLQE.

9. Preparation method and test representation for testing fluorescence lifetime of perovskite on different interfaces

FIG. 17 shows the steps for perovskite preparation on different charge transport materials. The fluorescence lifetime test of the luminescent film on different interfaces is based on 3 structures of a quartz substrate, a charge transport layer PVK and a charge transport layer TFB/LiF, the size of a quartz plate is 12mm x 12mm, and the quartz plate is subjected to ultrasonic cleaning for 15 minutes by using steps of deionized water, acetone, isopropanol, deionized water and isopropanol before use. The cleaned quartz plate was placed in a UV-Ozone cleaning machine for 15 minutes of Ozone cleaning.

The perovskite precursor solution is PEA_nCsPb_nBr_3n+1Consisting of 110mg of lead bromide (PbBr)₂) 64mg of cesium bromide (CsBr) and 24mg of 2-phenethylammonium bromide (PEABr) were dissolved in 1mL of a dimethyl sulfoxide (DMSO) solution at a concentration of 0.3 mol/L, and the solution was stirred on a 60 ℃ hot plate for 1 hour.

Directly spin coating perovskite solution for perovskite samples without charge transport layers and interfaces.

Secondly, for a sample added with the charge transport layer PVK, spin coating the charge transport material PVK, wherein the charge transport material PVK is dissolved in chlorobenzene solution (CB for short) and has the concentration of 6mg/ml, when the charge transport material PVK is coated, a liquid transfer gun with the dosage of 100uL is used for sucking 30uL of charge transport solution to coat the charge transport solution on quartz glass, a vacuum spin coating machine is started to spin coat the charge transport material on the quartz glass at the rotating speed of 3000 rpm/s for 60s, and the quartz glass after the charge transport material is spin-coated is placed on a hot table to be annealed at 120 ℃ for 10min, so that a flat charge transport material PVK film with the thickness of 10nm is obtained. And then sucking 30uL of perovskite solution by using a liquid-transferring gun with the range of 100uL to coat the perovskite solution on quartz glass, starting a vacuum spin-coating machine to spin-coat for 60s at the rotating speed of 3000 rpm/s, placing the quartz glass of the perovskite material after spin-coating on a hot table to anneal for 10min at the temperature of 60 ℃ to obtain a flat perovskite material film with the thickness of 35 nm.

Thirdly, for the sample added with the charge transport layer TFB/LiF, firstly, the charge transport material TFB is required to be spun, the charge transport material TFB is dissolved in chlorobenzene solution (CB for short) and has the concentration of 6mg/ml, when the charge transport material TFB is coated, 30uL of charge transport solution is absorbed by a liquid transfer gun with the dosage of 100uL and coated on quartz glass, a vacuum spin-coating machine is started to spin-coat for 60s at the rotating speed of 3000 rpm/s, the quartz glass which is spun to finish the charge transport material is placed on a hot table to be annealed at 120 ℃ for 10min, and the flat charge transport material TFB film with the thickness of 10nm is obtained.

Then the quartz plate is transferred to a glove box filled with high-purity nitrogen, and then transferred to a vacuum coating machine for polar interface LiF evaporation. The pressure of vacuum evaporation is 5 x10^-4Pa, the evaporation rate is measured by a quartz crystal oscillation plate, the evaporation rate is 0.01nm/s, the evaporation thickness of the polar interface is 1nm, and the quartz plate with the evaporated polar interface is transferred to a glove box filled with high-purity nitrogen to spin-coat the perovskite material.

Absorbing 30uL of perovskite solution by using a liquid-transferring gun with the range of 100uL, coating the perovskite solution on quartz glass, starting a vacuum spin-coating machine to spin at the rotating speed of 3000 rpm/s for 60s, placing the quartz glass of the perovskite material after spin-coating on a hot table, and annealing at the temperature of 60 ℃ for 10min to obtain a flat perovskite material film with the thickness of 35 nm.

The fluorescence lifetime measurement of the luminescent film is realized by a time-dependent single photon counter TCSPC, a prepared film sample quartz plate is placed on a fluorescence lifetime measurement sample test frame, a 405 nm pulse laser is used for exciting a sample, the frequency range of the pulse laser is 20 kHz-2 MHz, the average power of the pulse laser at 2MHz is 6mW, the luminescence measurement of the sample film adopts a single photon counter probe for measurement, the probe is an avalanche photodiode APD, the power supply adopts + 12V, the multiplication factor of the avalanche photodiode is not adopted for reducing background noise signals introduced by the dark current of a detector, a differential amplification circuit is adopted for amplifying optical-electrical signals output by the APD, a pulse shaping circuit and a pulse filter circuit are used for pulse shaping, pulse filtering is further used for primary T-type amplification, and fluorescence-electrical signals with high signal-to-noise ratio are extracted, and inputting an electric signal into the TCSPC host through the coaxial cable to read the fluorescence lifetime of the luminescent film sample.

FIG. 18 shows the fluorescence lifetime of the perovskite at different interfaces in ns, with the vertical axis representing the Current density in mA cm at the corresponding voltage^-2. Compare PVThe fluorescence lifetime of K/perovskite, TFB/LiF/perovskite and perovskite is shown, wherein PVK and TFB are charge transport materials, LiF is a polar interface, perovskite is perovskite, the perovskite on a quartz substrate and the PVK substrate has the approximate fluorescence lifetime, and the perovskite on TFB/LiF has the longest fluorescence lifetime, which shows that LiF as the polar interface can induce the crystallization of the perovskite, regulate and control the growth process of the perovskite, further reduce the defect state density, and further increase the fluorescence lifetime.

10. Preparation method and test characterization of different-thickness polar interface device

FIG. 19 is a flow chart of the preparation of interfaces of different thicknesses. The light emitting diode is prepared on ITO conductive glass, the size of the ITO conductive glass is 12mm x 12mm, and the ITO conductive glass is subjected to ultrasonic cleaning for 15 minutes by 7 steps of deionized water, acetone, isopropanol, deionized water and isopropanol before use. The cleaned ITO conductive glass is placed in a UV-Ozone cleaning machine for Ozone cleaning for 15 minutes, then the ITO conductive glass is transferred to a glove box filled with high-purity nitrogen, and the ITO conductive glass is placed on a vacuum spin coating machine for spin coating of a charge transport material, wherein the name of the charge transport material is poly (9, 9-dioctyl fluorene-alt-N- (4-sec-butyl phenyl) -diphenylamine) (TFB for short). TFB is dissolved in chlorobenzene solution (CB for short), the concentration is 6mg/ml, when coating the charge transport material TFB, a liquid transfer gun with the dosage of 100uL is used for absorbing 30uL of charge transport solution to coat the ITO conductive glass, a vacuum spin-coating machine is started to spin-coat for 60s at the rotating speed of 3000 rpm/s, the ITO conductive glass after the charge transport material is spun is placed on a hot bench to be annealed at 120 ℃ for 10min, and the flat TFB film of the charge transport material is obtained.

And transferring the ITO conductive glass covered with the charge transfer material to a vacuum coating machine for polar interface LiF evaporation. The pressure of vacuum evaporation is 5 x10^-4Pa, the evaporation rate is measured by a quartz crystal oscillation plate, the evaporation rate is 0.01nm/s, and the polar interface LiF evaporation thickness is 0nm, 1nm, 2nm and 5 nm. And transferring the ITO conductive glass substrate subjected to the evaporation of the polar interface LiF to a glove box filled with high-purity nitrogen for perovskite solution spin coating.

Putting the ITO conductive glass coated with perovskite into a vacuum coating machine for vapor deposition of charge transport material with the name of 2,2' - (1, 3, 5-benzimidazole) -tri (1-phenyl-1-H-benzimidazole) (TPBi for short), wherein the pressure of vacuum vapor deposition is 5 x10^-4Pa, the evaporation rate is measured by a quartz crystal oscillating piece, the evaporation rate is 0.1 nm/s, and the thickness of TPBi is 40 nm.

After the charge transport material TPBi is evaporated, the evaporated metal mask is replaced, and the light emitting size can be limited to 5.25mm through the mask²The evaporation electrode materials of lithium fluoride LiF and Al are evaporated, the evaporation rate is measured by a quartz crystal oscillation plate, the evaporation rate of the lithium fluoride LiF is 0.01nm/s, the thickness of LiF is 1nm, and the evaporation rate of the metal aluminum Al is 100 nm.

The prepared device is tested by adopting an OLED photochromic and photoelectric testing system to test external quantum efficiency EQE, the efficiency test of the light-emitting diode is realized by an OLED 2000 photochromic and photoelectric external quantum efficiency testing system, the system comprises a luminance meter, a Giaxle source meter 2400, a computer upper computer, an industrial control camera CCD, a sample test board and the like, the luminance meter is used for detecting the spectrum and the spectrum power of the light-emitting diode, the Giaxle source meter 2400 serves as a power source of the light-emitting diode and plays the roles of power output and current detection, the positive and negative electrodes of the light-emitting diode are connected after the positive and negative electrodes are led out by the 2400, the voltage range loaded on the light-emitting device is 0V-8V, the voltage stepping interval is 0.1V, the current passing through the light-emitting diode is measured by a four-wire method, the current detection range is 1 nA-100 mA, and the current^-3– 10³mA/cm²Therefore, the current test requirement of the light emitting diode can be met. The computer upper computer realizes the function of interactive communication with the luminance meter, the Ji-Shi Source Meter 2400 and the industrial control camera CCD, acquires the acquired spectrum, the spectral power, the voltage, the current and the detection image, realizes the real-time display function, and the sample test bench bears the placement of the light emitting diode sample, thereby achieving the three-dimensional position adjusting function, ensuring clearer observation and more accurate measurement and realizing the purpose of optimizing performance test.

FIG. 20 shows the effect of different thickness interfaces on the charge injection capability with voltage applied across the LED on the horizontal axisVoltage is in V, and the vertical axis represents the Current density at the corresponding Voltage in mAcm^-2. After the LiF polar interface is added, the thickness of LiF is 0nm, 1nm, 2nm and 5nm, the charge transmission capability of the LiF polar interface is greatly improved, the current density is rapidly increased after 2V, which is shown as the current density slope increasing along with the voltage change, the charge injection capability of the LiF polar interface is enhanced, the slope of a specific current density curve along with the voltage change is higher than that of a non-LiF material, which shows that the ultra-thin LiF material can increase the effective charge injection, in addition, the charge transmission capability of the LiF polar interface is not changed after the interface thickness is changed, which shows that the polar interface is used as a tunneling layer, and the charge injection and the potential barrier increase cannot be influenced.

11. Preparation method and test characterization of polar interface for light-emitting device

Fig. 21 is a flow chart of a light emitting diode device fabrication process. The light emitting diode is prepared on ITO conductive glass, the size of the ITO conductive glass is 12mm x 12mm, and the ITO conductive glass is subjected to ultrasonic cleaning for 15 minutes by 7 steps of deionized water, acetone, isopropanol, deionized water and isopropanol before use. The cleaned ITO conductive glass is placed in a UV-Ozone cleaning machine for Ozone cleaning for 15 minutes, then the ITO conductive glass is transferred to a glove box filled with high-purity nitrogen, and the ITO conductive glass is placed on a vacuum spin coating machine for spin coating of a charge transport material, wherein the name of the charge transport material is poly (9, 9-dioctyl fluorene-alt-N- (4-sec-butyl phenyl) -diphenylamine) (TFB for short). TFB is dissolved in chlorobenzene solution (CB for short), the concentration is 6mg/ml, when coating the charge transport material TFB, a liquid transfer gun with the dosage of 100uL is used for absorbing 30uL of charge transport solution to coat the ITO conductive glass, a vacuum spin-coating machine is started to spin-coat for 60s at the rotating speed of 3000 rpm/s, the ITO conductive glass after the charge transport material is spun is placed on a hot bench to be annealed at 120 ℃ for 10min, and the flat TFB film of the charge transport material is obtained.

And transferring the ITO conductive glass covered with the charge transfer material to a vacuum coating machine for polar interface LiF evaporation. The pressure of vacuum evaporation is 5 x10^-4Pa, the evaporation rate is measured by a quartz crystal oscillating pieceThe speed is 0.01nm/s, and the evaporation thickness of the polar interface LiF is 1 nm. And transferring the ITO conductive glass substrate subjected to the evaporation of the polar interface LiF to a glove box filled with high-purity nitrogen for perovskite solution spin coating.

The perovskite precursor solution is PEA_nCsPb_nBr_3n+1Consisting of 110mg of lead bromide (PbBr)₂) 64mg of cesium bromide (CsBr) and 24mg of 2-phenethylammonium bromide (PEABr) were dissolved in 1mL of a dimethyl sulfoxide (DMSO) solution at a concentration of 0.3 mol/L, and the solution was stirred on a 60 ℃ hot plate for 1 hour. During spin coating, the ITO conductive glass is placed on a vacuum spin coater, 30uL of solution is absorbed by 100uL of dosage range and coated on the ITO conductive glass evaporated with the polar interface and the charge transmission material, a button of the vacuum spin coater is started to spin coat for 60s at the rotating speed of 3000 rpm/s, and the smooth perovskite thin film can be obtained after annealing at the temperature of 60 ℃ for 10 min.

The prepared device adopts an OLED photochromic and photoelectric testing system to test external quantum efficiency EQE during testing, the efficiency test of the light-emitting diode is realized by an OLED 2000 photochromic and photoelectric external quantum efficiency testing system, the system comprises a luminance meter, a Giaxle power meter 2400, a computer upper computer, an industrial control camera CCD, a sample test board and the like, the luminance meter is used for detecting the spectrum and the spectrum power of the light-emitting diode, the Giaxle power meter 2400 serves as a power source of the light-emitting diode and plays the roles of power output and current detection, and the positive and negative electrodes are led out by the 2400 and connected after being connected with a wiringThe voltage range loaded on the light-emitting device is 0V-8V, the voltage stepping interval is 0.1V, the current passing through the light-emitting diode is measured by a four-wire method, the current detection range is 1 nA-100 mA, and the current density range is 10^-3– 10³mA/cm²Therefore, the current test requirement of the light emitting diode can be met. The computer upper computer realizes the function of interactive communication with the luminance meter, the Ji-Shi Source Meter 2400 and the industrial control camera CCD, acquires the acquired spectrum, the spectral power, the voltage, the current and the detection image, realizes the real-time display function, and the sample test bench bears the placement of the light emitting diode sample, thereby achieving the three-dimensional position adjusting function, ensuring clearer observation and more accurate measurement and realizing the purpose of optimizing performance test.

FIG. 22 shows device efficiency based on polar interfacial transport materials and other transport materials, with Current density through the LED in mA cm on the horizontal axis^-2The ordinate represents the external quantum efficiency EQE in%. The light-emitting diode is in an ITO/HTL/Perovskite/TPBi/LiF/Al structure, wherein the HTL is a hole transport material and is respectively in a TFB/LiF structure and a PVK structure, and the curve shows that the hole mobility of the TFB is higher than that of the PVK structure, so that the higher hole mobility can increase the transport capability of charges under low voltage. The deposition of polar interface LiF on TFB has the highest efficiency, indicating that replacing PVK with LiF allows better injection of charge into the perovskite functional material, reducing the barrier between the transport material interface and the perovskite material.

Claims

1. A halide perovskite optoelectronic device based on a polar interface, characterized in that: the preparation process of the perovskite luminescent thin film luminescent device comprises the following steps:

2. The polar interface based halide perovskite optoelectronic device of claim 1, wherein: the polar interface material is composed of a plurality of compounds, including polar interface materials capable of forming compounds during different periods, polar interface materials capable of forming compounds among different groups, strong polar interface materials capable of forming compounds among different groups, and other interface materials matched with perovskite materials.

3. A polar interface based halide perovskite optoelectronic device as claimed in claim 2 wherein: polar interface materials that can form compounds during different cycles include metal oxide material interface ZrO₂、V₂O₅、Al₂O₃、NiO、MoO₃、ZnO、MgO、NiO、SnO₂(ii) a The polar interface material capable of forming compound between different groups comprises carbonate metal compound material Li₂CO₃、Na₂CO₃、 Cs₂CO₃(ii) a The strong polar interface materials which can form compounds among different groups comprise metal fluoride material interfaces LiF, NaF, KF, RbF, CsF and MgF₂、CaF₂(ii) a Other interface materials that interact with perovskite materials include PTFE, piezoelectric films, piezoelectric ceramics.

4. The polar interface based halide perovskite optoelectronic device of claim 1, wherein: preparing a conductive perovskite luminescent thin film luminescent device with ITO:

5. A polar interface based halide perovskite optoelectronic device as claimed in claim 1 or 4 wherein: the preparation method of the polar interface on the substrate adopts magnetron sputtering, MOCVD, ALD, spraying, printing or chemical synthesis methods, and the thickness range is 0.1 nm-1000 nm.

6. A polar interface based halide perovskite optoelectronic device as claimed in claim 1 or 4 wherein: the polarity of the polar interface material is changed by regulating and controlling materials with different electronegativities, or a non-polar interface is regulated and controlled to be a polar interface, and finally the final performance of the device is regulated and controlled by changing the polarity mode of the material interface.

7. A polar interface based halide perovskite optoelectronic device as claimed in claim 1 or 4 wherein: the polar material interface is applied to various photoelectric devices, including solar cells, light emitting diodes, detectors, fluorescent films, fluorescent powder, semiconductor transistors, lasers and other photoelectric devices and materials.

8. A polar interface based halide perovskite optoelectronic device as claimed in claim 1 or 4 wherein: the polar material interface can be applied to defining the effective working area of perovskite materials or devices, further defining different working patterns, and can be expanded to be applied to perovskite materials and photoelectric devices based on different patterns.