Photoelectric sensor and its manufacturing method, and display device

Abstract

The present disclosure provides a photoelectric sensor and a preparation method thereof, and a display device, which belongs to the field of display technology, and can solve the problem that the perovskite layer in the existing photoelectric sensor itself has many pinholes, metal ion vacancies and other defects that increase the dark current. A photoelectric sensor disclosed in the present disclosure includes: a substrate, a first electrode and a second electrode located on the substrate and arranged opposite to each other, and a photosensitive layer located between the first electrode and the second electrode; the photosensitive layer includes: a perovskite layer; gaps are formed between the perovskite grains on the side of the perovskite layer away from the substrate; the photosensitive layer also includes: a first organic auxiliary layer; the first organic auxiliary layer includes: a first organic heterojunction material, and the first organic auxiliary layer is filled in the gaps between the perovskite grains.

Description

Technical Field

[0001] The present disclosure belongs to the field of display technology, and specifically relates to a photoelectric sensor and a preparation method thereof, and a display device. Background Art

[0002] With the continuous development of display technology, in order to meet the needs of users, photoelectric sensors have been used more and more widely. For example, photoelectric sensors are used to receive light reflected by fingerprints to achieve fingerprint recognition, or photoelectric sensors are used to receive ambient light to adjust the display brightness of the display screen in different ambient light. Due to the advantages of perovskite such as adjustable band gap, simple preparation process and low cost, photoelectric sensors with perovskite materials as photosensitive layers have become a current research hotspot.

[0003] However, the perovskite layer in current photoelectric sensors itself has many defects such as pinholes and metal ion vacancies, which increase the dark current and hinder the separation of electron-hole pairs, which is not conducive to further improving the performance of photoelectric sensors. Summary of the invention

[0004] The present disclosure aims to solve at least one of the technical problems existing in the prior art and provide a photoelectric sensor and a preparation method thereof, and a display device.

[0005] In a first aspect, an embodiment of the present disclosure provides a photoelectric sensor, the photoelectric sensor comprising: a substrate, a first electrode and a second electrode located on the substrate and arranged opposite to each other, and a photosensitive layer located between the first electrode and the second electrode;

[0006] The photosensitive layer includes: a perovskite layer; gaps are formed between the perovskite grains on the side of the perovskite layer away from the substrate; the photosensitive layer also includes: a first organic auxiliary layer;

[0007] The first organic auxiliary layer includes: a first organic heterojunction material, and the first organic auxiliary layer is filled in the gaps between the perovskite grains.

[0008] Optionally, the photosensitive layer further comprises: a second organic auxiliary layer;

[0009] The second organic auxiliary layer includes: a second organic heterojunction material, and the second organic auxiliary layer is located on a side of the first organic auxiliary layer away from the substrate.

[0010] Optionally, the first organic heterojunction material is the same as the second organic heterojunction material.

[0011] Optionally, the thickness of the first organic auxiliary layer is less than or equal to the gap depth between the perovskite grains in the perovskite layer;

[0012] The thickness of the second organic auxiliary layer is less than or equal to the thickness of the perovskite layer.

[0013] Optionally, the doping ratio of the organic heterojunction material in the perovskite layer is 1 wt % to 30 wt %.

[0014] Optionally, the organic heterojunction material comprises: a donor material and an acceptor material;

[0015] The mass of the donor material is equal to the mass of the acceptor material.

[0016] Optionally, the donor material includes: a macromolecular organic donor material;

[0017] The receptor material includes: small molecule organic receptor material.

[0018] Optionally, the photoelectric sensor further comprises: a hole transport layer and an electron transport layer;

[0019] The hole transport layer is located on a side of the first electrode close to the perovskite layer;

[0020] The electron transport layer is located on a side of the second electrode close to the perovskite layer.

[0021] In a second aspect, an embodiment of the present disclosure provides a display device, the display device comprising: a plurality of display devices and a plurality of photoelectric sensors as provided above;

[0022] The photosensor is located between at least part of the adjacent display devices.

[0023] In a third aspect, an embodiment of the present disclosure provides a method for preparing a photoelectric sensor, the method for preparing the photoelectric sensor comprising:

[0024] forming a first electrode on a substrate;

[0025] A perovskite layer is formed on the first electrode; gaps are formed between perovskite grains on a side of the perovskite layer facing away from the substrate;

[0026] annealing the perovskite layer using a first organic heterojunction material solution as an anti-solvent to form a first organic auxiliary layer;

[0027] A second electrode is formed on the first organic auxiliary layer.

[0028] Optionally, before forming a second electrode on the first organic auxiliary layer, the method further includes:

[0029] The perovskite layer is annealed using a second organic heterojunction material solution as an anti-solvent to form a second organic auxiliary layer; wherein the concentration of the second organic heterojunction material solution is greater than the concentration of the first organic heterojunction material solution.

[0030] Optionally, the solvents of the first organic heterojunction material solution and the second organic heterojunction material solution both include: chlorobenzene;

[0031] The solutes of the first organic heterojunction material solution and the second organic heterojunction material solution both include: a donor material and an acceptor material.

[0032] Optionally, the donor material includes: a macromolecular organic donor material;

[0033] The receptor material includes: small molecule organic receptor material.

[0034] Optionally, the concentration of the first organic heterojunction material solution is less than or equal to 30 mg / mL;

[0035] The concentration of the second organic heterojunction material solution is greater than 30 mg / mL and less than or equal to 100 mg / mL. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a schematic diagram of the structure of an exemplary photoelectric sensor;

[0037] Figure 2 A schematic diagram of the structure of a photoelectric sensor provided in an embodiment of the present disclosure;

[0038] Figure 3 A schematic diagram of the structure of another photoelectric sensor provided in an embodiment of the present disclosure;

[0039] Figure 4 A dark current comparison diagram of a photoelectric sensor provided by an embodiment of the present disclosure;

[0040] Figure 5 A dark current comparison diagram of another photoelectric sensor provided in an embodiment of the present disclosure;

[0041] Figure 6 A dark current comparison diagram of another photoelectric sensor provided in an embodiment of the present disclosure;

[0042] Figure 7 A schematic diagram of a process for preparing a photoelectric sensor provided in an embodiment of the present disclosure;

[0043] Figure 8 A schematic flow chart of another method for preparing a photoelectric sensor provided in an embodiment of the present disclosure;

[0044] Figure 9a This is the surface morphology of the perovskite layer when the perovskite film layer is annealed using CB;

[0045] Figure 9b This is the cross-sectional morphology of the perovskite layer when the perovskite film layer is annealed using CB;

[0046] Fig.10a and Fig.10b Surface morphology of the photosensor when the perovskite layer was annealed using CB solution of 5 mg / mL P3HT & 5 mg / mL PCBM;

[0047] Fig.10c The cross-sectional morphology of the photosensor when the perovskite layer was annealed using a CB solution of 5 mg / mL P3HT & 5 mg / mL PCBM;

[0048] Fig.11a and Fig.11b Surface morphology of the photosensor when the perovskite layer was annealed using CB solution of 15 mg / mL P3HT & 15 mg / mL PCBM;

[0049] Fig.11c The cross-sectional morphology of the photosensor when the perovskite layer was annealed using a CB solution of 15 mg / mL P3HT & 15 mg / mL PCBM;

[0050] Fig.12a and Figure 12b Surface morphology of the photosensor when the perovskite layer was annealed using CB solution of 50 mg / mL P3HT & 50 mg / mL PCBM;

[0051] Fig.12c This is the cross-sectional morphology of the photosensor when the perovskite layer was annealed using a CB solution of 50 mg / mL P3HT & 50 mg / mL PCBM. DETAILED DESCRIPTION

[0052] In order to enable those skilled in the art to better understand the technical solution of the present disclosure, the present disclosure is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0053] Unless otherwise defined, the technical terms or scientific terms used in the present disclosure should be understood by people with ordinary skills in the field to which the present disclosure belongs. The "first", "second" and similar words used in the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, similar words such as "one", "one" or "the" do not indicate quantity restrictions, but indicate that there is at least one. Similar words such as "include" or "comprise" mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Similar words such as "connect" or "connected" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0054] Figure 1 is a schematic diagram of an exemplary structure of a photoelectric sensor, such as Figure 1 As shown, the photoelectric sensor includes: a substrate 100 , a first electrode 101 and a second electrode 102 located on the substrate 100 and arranged opposite to each other, and a photosensitive layer 103 located between the first electrode 101 and the second electrode 102 ; the photosensitive layer 103 includes: a perovskite layer 1030 .

[0055] It should be noted that, according to the materials and arrangement of the first electrode 101 and the second electrode 102 in the photoelectric sensor, the photoelectric sensor can be divided into a bottom emission photoelectric sensor and a top emission photoelectric sensor. For the convenience of description, in the embodiments of the present disclosure and the following description, the bottom emission photoelectric sensor will be used as an example for description. It is understandable that the structure and implementation principle of the top emission photoelectric sensor are similar and will not be described in detail.

[0056] When no light is irradiated to the photosensitive layer 103 in the photoelectric sensor, that is, the perovskite layer 1030, the reverse current between the first electrode 101 and the second electrode 102 is extremely weak, which is called dark current. When light is irradiated to the perovskite layer 1030, the electrons in the perovskite layer 1030 absorb the energy of the photons, and the photon energy is transferred to the electrons. After the electrons receive the energy transferred by the photons, their state changes and a photoelectric effect occurs. At this time, the reverse current between the first electrode 101 and the second electrode 102 increases, so that the light signal can be converted into a current signal or a voltage signal to achieve photoelectric conversion.

[0057] However, the surface of the perovskite layer 1030 in the current photoelectric sensor is uneven, and it has many defects such as pinholes and metal ion vacancies, which increase the dark current and hinder the separation of electron-hole pairs, which is not conducive to further improving the performance of the photoelectric sensor.

[0058] In order to solve at least one of the above-mentioned technical problems, the embodiments of the present disclosure provide a photoelectric sensor and a method for preparing the same, and a display device. The photoelectric sensor and a method for preparing the same, and the display device provided in the embodiments of the present disclosure will be further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0059] In a first aspect, an embodiment of the present disclosure provides a photoelectric sensor. Figure 2 A schematic diagram of the structure of a photoelectric sensor provided in an embodiment of the present disclosure is shown in FIG. Figure 2 As shown, the photoelectric sensor includes: a substrate 100, a first electrode 101 and a second electrode 102 located on the substrate 100 and arranged opposite to each other, and a photosensitive layer 103 located between the first electrode 101 and the second electrode 102; the photosensitive layer 103 includes: a perovskite layer 1030; gaps are formed between the perovskite grains on the side of the perovskite layer 1030 away from the substrate 100; the photosensitive layer 103 also includes: a first organic auxiliary layer 1031; the first organic auxiliary layer 1031 includes: a first organic heterojunction material, and the first organic auxiliary layer 1031 is filled in the gaps between the perovskite grains.

[0060] The substrate 100 can be made of a rigid material such as glass, which can improve the bearing capacity of the substrate 100 for other film layers thereon. Of course, the substrate 100 can also be made of a flexible material such as polyimide (PI), which can improve the overall bending and stretching resistance of the photoelectric sensor, and avoid the stress generated during bending, stretching, and twisting that causes the substrate 100 to break and cause a short circuit. In practical applications, the material of the substrate 100 can be reasonably selected according to actual needs to ensure that the photoelectric sensor has good performance.

[0061] The polarities of the first electrode 101 and the second electrode 102 are opposite, wherein the first electrode 101 can be specifically an anode of a photoelectric sensor, and the anode can be made of a transparent material such as polyimide (ITO) to facilitate the irradiation of light from the anode. The second electrode 102 can be specifically a cathode of a photoelectric sensor, and the cathode can be made of at least one of metal materials such as silver (Ag), aluminum (Al), and titanium (Ti). It can be a single-layer structure made of the above-mentioned single material, or a multi-layer structure made of the above-mentioned multiple materials. The cathode is a non-transparent structure, which is conducive to reflecting light.

[0062] The material of the perovskite layer 1030 can be one or more of a typical halogen perovskite material with a chemical formula of ABM3, a halogen-substituted solid solution perovskite material with a chemical formula of ABM1xM23-x (0<X<3), a monovalent cation-substituted perovskite material with a chemical formula of A1xA21-xBM (0<X<1), a metal-substituted solid solution perovskite material with a chemical formula of AB1xB21-xM (0<X<1), and a two-dimensional perovskite material, wherein A, A1, and A2 are monovalent non-coordinating cations, B, B1, and B2 are divalent P-block metals, and M, M1, and M2 are halogen anions coordinated with metals. Due to the crystal characteristics of the perovskite material, gaps are formed between the perovskite grains on the side of the perovskite layer 1030 facing away from the substrate 100 after crystallization.

[0063] The first organic auxiliary layer 1031 is composed of an organic heterojunction material, which can be formed by P-type organic material and N-type organic material, can be filled in the gaps between perovskite grains, and can further absorb light. Its specific material composition will be further described in detail in subsequent embodiments and will not be described in detail here.

[0064] In the photoelectric sensor provided by the embodiment of the present disclosure, the first organic auxiliary layer 1031 is composed of an organic heterojunction material and can be filled in the gaps between the perovskite grains of the perovskite layer 1030. The first organic auxiliary layer 1031 can passivate the surface of the perovskite layer 1030 to prevent the generation of defects such as pinholes and metal ion vacancies, so as to avoid the above defects hindering the separation of electron-hole pairs. Therefore, the problem of large dark current and low switching ratio of the photoelectric sensor can be solved, thereby improving the photoelectric conversion performance of the photoelectric sensor.

[0065] At the same time, the organic heterojunction material in the first organic auxiliary layer 1031 can further absorb light, and can achieve higher responsiveness and wider response bandwidth, thereby further improving the photoelectric conversion performance of the light sensor.

[0066] Figure 3 A schematic diagram of the structure of another photoelectric sensor provided in an embodiment of the present disclosure is shown in FIG. Figure 3 As shown, the photosensitive layer 103 further includes: a second organic auxiliary layer 1032 ; the second organic auxiliary layer 1032 includes: a second organic heterojunction material, and the second organic auxiliary layer 1032 is located on a side of the first organic auxiliary layer 1031 away from the substrate 101 .

[0067] The second organic auxiliary layer 1032 can form a separate film layer on the perovskite layer 1030, and can further passivate the surface of the perovskite layer 1030 to further reduce the dark current of the photoelectric sensor, thereby further improving the photoelectric conversion performance of the photoelectric sensor. The first organic heterojunction material and the second organic heterojunction material can be the same. When preparing the first organic auxiliary layer 1031 and the second organic auxiliary layer 1032, the same process can be used to prepare them to reduce the process steps and save the preparation cost. For example, the perovskite layer 1030 can be annealed using a solution in which the organic heterojunction material is used as an anti-solvent to form the first organic auxiliary layer 1031 and the second organic auxiliary layer 1032. Whether the second organic auxiliary layer 1032 is formed and how thick the second organic auxiliary layer 1032 is are related to the concentration of the organic heterojunction material in the solution, and can be adjusted by adjusting the concentration of the organic heterojunction material in the solution.

[0068] In some embodiments, the thickness of the first organic auxiliary layer 1031 is less than or equal to the gap depth between the perovskite grains in the perovskite layer 1030 ; and the thickness of the second organic auxiliary layer 1032 is less than or equal to the thickness of the perovskite layer 1030 .

[0069] In practical applications, the thickness of the first organic auxiliary layer 1031 can be less than the gap depth between the perovskite grains in the perovskite layer 1030, and only a small part of the organic heterojunction material is filled in the gap, which can have a certain effect on reducing the dark current, but the effect is not obvious. The thickness of the first organic auxiliary layer 1031 can be equal to the gap depth between the perovskite grains in the perovskite layer 1030, so that the organic heterojunction material can be completely filled in the gap, which can effectively reduce the dark current of the photoelectric sensor. The thickness of the second organic auxiliary layer 1032 can be less than or equal to the thickness of the perovskite layer 1030, and a film layer can be formed separately on the surface of the perovskite layer 1030. While filling the gaps between the perovskite grains, the surface of the perovskite layer 1030 can be passivated, thereby further reducing the dark current of the photoelectric sensor.

[0070] In some embodiments, the doping ratio of the organic heterojunction material in the perovskite layer 1030 is 1 wt % to 30 wt %.

[0071] It should be noted that the doping ratio of the organic heterojunction material in the perovskite layer 1030 can be set according to actual needs, for example, it can be 1wt% to 30wt%. When the doping ratio of the organic heterojunction material in the perovskite layer 1030 is 1wt%, only the first organic auxiliary layer 1031 can be formed, the content of the organic heterojunction material in the perovskite layer 1030 is small, and the second organic auxiliary layer 1032 will not be formed, which only reduces the dark current of the photoelectric sensor to a certain extent. The comparison diagram of the dark current is shown in FIG. Figure 4 When the doping ratio of the organic heterojunction material in the perovskite layer 1030 is 2wt% to 5wt%, only the first organic auxiliary layer 1031 can be formed, and the content of the organic heterojunction material in the perovskite layer 1030 is relatively high, which can effectively reduce the dark current of the photoelectric sensor. The dark current comparison diagram is shown in FIG. Figure 5 When the doping ratio of the organic heterojunction material in the perovskite layer 1030 is 30wt%, not only the first organic auxiliary layer 1031 can be formed, but also the second organic auxiliary layer 1032 can be formed separately, and the surface of the perovskite layer 1030 can be further passivated to further reduce the dark current of the photoelectric sensor. The dark current comparison diagram is shown in FIG. Figure 6 shown.

[0072] In some embodiments, the organic heterojunction material includes: a donor material and an acceptor material; the mass of the donor material is equal to the mass of the acceptor material.

[0073] The donor material may be a macromolecular organic donor material. The molecular weight of the macromolecular organic donor material is generally large, for example, it may be above 5000, and it may specifically be at least one of P3HT, PTB7-Th, and PCDTBT. The acceptor material may be a small molecule organic acceptor material. The molecular weight of the small molecule organic acceptor material is generally small, for example, it may be below 1000, and it may specifically be a fullerene acceptor material, such as at least one of

[60] PCBM and

[70] PCBM, or a non-fullerene small molecule organic material may be selected, such as at least one of ITIC, ITIC-4F, eh-IDTBR, and O-IDTBR. For the ratio of the donor material to the acceptor material, a mass ratio of the donor material to the acceptor material of 1:1 may be selected. It is to be understood that the donor material and the acceptor material are not limited to the materials exemplified above, and may also include materials having the same or similar properties as the above materials, which will not be listed one by one here.

[0074] In practical applications, the mass ratio of the acceptor material can also be increased so that the mass of the donor material is less than that of the acceptor material. For example, the mass ratio of the donor material to the acceptor material can be 5:95, 1:20, etc. In extreme cases, only the acceptor material can be used.

[0075] In practical applications, the mass ratio of the donor material can also be increased so that the mass of the donor material is greater than that of the acceptor material. For example, the mass ratio of the donor material to the acceptor material can be 95:5, 25:1, etc. In the extreme case, only the donor material is used.

[0076] In some embodiments, Figure 2 and Figure 3As shown, the photoelectric sensor further includes: a hole transport layer 104 and an electron transport layer 105 ; the hole transport layer 104 is located on the side of the first electrode 101 close to the perovskite layer 1030 ; the electron transport layer 105 is located on the side of the second electrode 102 close to the perovskite layer 1030 .

[0077] The material of the hole transport layer 104 can be at least one of PEDOT, PSS, CuSCN, CuI, NiOx, MoO3, and spiro-OMeTAD, which has good hole transport capability and can ensure that the holes separated from the electron-hole pairs can be transported to the first electrode 101. The material of the electron transport layer 105 can be at least one of fullerene and its derivatives, TiO2, ZnO, and SnO2, which has good electron transport capability and can ensure that the electrons separated from the electron-hole pairs can be transported to the second electrode 102. In this way, the separation of electron-hole pairs can be further guaranteed, and the photoelectric conversion performance of the photoelectric sensor can be improved. It can be understood that in order to further improve the photoelectric conversion performance of the photoelectric sensor, other film layers such as a hole injection layer and an electron injection layer can also be set to further improve the transmission performance of holes and electrons. The setting method can refer to the relevant technology and will not be repeated here.

[0078] In a second aspect, an embodiment of the present disclosure provides a display device, the display device comprising: a plurality of display devices and a plurality of photoelectric sensors as provided in any of the above embodiments, the photoelectric sensors being located between at least some of the adjacent display devices. The display device may specifically be any product or component with a display function, such as a mobile phone, a tablet computer, a television, a computer monitor, a laptop computer, a digital photo frame, a navigator, etc., and its implementation principle and beneficial effects are the same as those of the above photoelectric sensors, and will not be described in detail here.

[0079] In a third aspect, the present disclosure provides a method for preparing a photoelectric sensor. Figure 7 A schematic diagram of a process for preparing a photoelectric sensor provided in an embodiment of the present disclosure is shown in FIG. Figure 7 As shown, the method for preparing the photoelectric sensor includes the following steps S701 to S704.

[0080] S701, forming a first electrode on a substrate.

[0081] In step S701, a conductive layer is formed on the substrate. The material of the conductive layer may be a transparent material such as indium tin oxide (ITO). The conductive layer is then patterned to form a pattern of a first electrode.

[0082] S702, forming a perovskite layer on the first electrode; gaps are formed between the perovskite grains on the side of the perovskite layer facing away from the substrate.

[0083] In step S702, the perovskite material can be spin-coated at a rotation speed of 4000 rpm for 30 seconds using a spin coating process, and 200 μL of anti-solvent chlorobenzene (CB) is quickly added 10 seconds after the start of spin coating. After the spin coating is completed, it is quickly transferred to a heating table at 150° C. and heated for 20 minutes under an inert gas state for standby use to form a perovskite layer. The material of the perovskite layer can be specifically a typical halogen perovskite material with a chemical formula of ABM3, a halogen-substituted solid solution perovskite material with a chemical formula of ABM1xM23-x (0<X<3), a monovalent cation-substituted perovskite material with a chemical formula of A1xA21-xBM (0<X<1), a metal-substituted solid solution perovskite material with a chemical formula of AB1xB21-xM (0<X<1), or one or more of a two-dimensional perovskite material, wherein A, A1, and A2 are monovalent non-coordinating cations, B, B1, and B2 are divalent P-block metals, and M, M1, and M2 are halogen anions coordinated with metals. Due to the crystal characteristics of the perovskite material, gaps are formed between the perovskite grains on the side of the perovskite layer 1030 facing away from the substrate 100 after crystallization.

[0084] S703 , using the first organic heterojunction material solution as an anti-solvent, annealing the perovskite layer to form a first organic auxiliary layer.

[0085] In step S703, for the anti-solvent first organic heterojunction solution, the solute consists of two parts, namely, a donor material and an acceptor material, and the solvent can be composed of chlorobenzene (CB). The donor material can be a macromolecular organic donor material, and the molecular weight of the macromolecular organic donor material is generally large, for example, it can be more than 5000, and it can be specifically at least one of P3HT, PTB7-Th, and PCDTBT. The acceptor material can be a small molecule organic acceptor material, and the molecular weight of the small molecule organic acceptor material is generally small, for example, it can be less than 1000, and it can be specifically fullerene acceptor materials, such as at least one of

[60] PCBM and

[70] PCBM, or non-fullerene small molecule organic materials, such as at least one of ITIC, ITIC-4F, eh-IDTBR, and O-IDTBR. For the ratio of the donor material to the acceptor material in the solution, a 1:1 mass ratio of the donor material to the acceptor material can be selected; or the mass ratio of the acceptor material can be increased, such as 5:95, 1:20, etc., and only the acceptor material is used in the limit state; or the mass ratio of the donor material can be increased, such as 95:5, 25:1, etc., and only the donor material is used in the limit state. The organic heterojunction material in the solution is precipitated and filled in the gaps between the perovskite grains to form the first organic auxiliary layer

[0086] S704, forming a second electrode on the first organic auxiliary layer.

[0087] In step S704, a conductive layer is formed on the first organic auxiliary layer. The material of the conductive layer may be at least one of metal materials such as silver (Ag), aluminum (Al), titanium (Ti), etc. The conductive layer is then patterned to form a pattern of the second electrode.

[0088] In some embodiments, Figure 8 As shown, before step S704, it also includes S703a, using a second organic heterojunction material solution as an anti-solvent to anneal the perovskite layer to form a second organic auxiliary layer; wherein the concentration of the second organic heterojunction material solution is greater than the concentration of the first organic heterojunction material solution.

[0089] The doping amount of the organic heterojunction material in the perovskite layer increases with the increase in the concentration of the organic heterojunction solution. Since the organic heterojunction solution is prepared using the more conventional chlorobenzene, the solubility is relatively large. Taking the P3HT / PCBM solution as an example, the total concentration can reach 100 mg / mL when the ratio is 1:1. At this time, a thicker and separate second organic auxiliary layer will be formed on the first organic auxiliary layer. The total doping ratio of the organic heterojunction material can reach more than 30wt% (including the second organic auxiliary layer). The comparison chart of its dark current is as follows: Figure 6 As shown. When the solution concentration is reduced, the second organic auxiliary layer alone is rapidly thinned. When the total concentration is 30 mg / mL at a ratio of 1:1, no obvious second organic auxiliary layer is observed. However, in the cross-sectional view of the perovskite layer, it is observed that a large amount of organic heterojunction materials are doped in the gaps between the perovskite grains. At this time, the doping ratio is about 2 wt% to 5 wt%. The dark current comparison diagram is shown in Figure 5 When the total concentration of the ratio is less than 10 mg / mL, the organic heterojunction material between the perovskite grains is less doped, and the doping ratio is less than 1wt%. The comparison diagram of the dark current is shown in Figure 4 shown.

[0090] The structure and performance of the photoelectric sensor formed by converting the perovskite layer using organic heterojunction material solutions of different concentrations will be described in detail below in conjunction with the accompanying drawings.

[0091] Figure 9a This is the surface morphology of the perovskite layer when the perovskite film layer is annealed using CB. Figure 9b This is a cross-sectional morphology of the perovskite layer when the perovskite film layer is annealed using CB, as shown in Figure 9a and Figure 9b As shown, when the perovskite film layer is annealed using CB, the surface of the perovskite layer has many defects such as pinholes and metal ion vacancies, which increase the dark current and hinder the separation of electron-hole pairs, which is not conducive to further improving the performance of the photoelectric sensor.

[0092] Fig.10a and Fig.10b The surface morphology of the photoelectric sensor when the perovskite layer was annealed using a CB solution of 5 mg / mL P3HT & 5 mg / mL PCBM. Fig.10c The cross-sectional morphology of the photoelectric sensor when the perovskite layer was annealed using a CB solution of 5 mg / mL P3HT & 5 mg / mL PCBM. Figures 10a to 10c It can be seen that when the perovskite layer is annealed using a CB solution of 5 mg / mL P3HT & 5 mg / mL PCBM, part of the pinhole structure on the surface of the perovskite layer can be filled with organic heterojunction materials. The content of organic heterojunction materials in the perovskite layer is relatively small, and no second organic auxiliary layer is formed, which only reduces the dark current of the photoelectric sensor to a certain extent. The comparison of the dark current is shown in the figure below. Figure 4 shown.

[0093] Fig.11a and Fig.11b The surface morphology of the photoelectric sensor when the perovskite layer was annealed using a CB solution of 15 mg / mL P3HT & 15 mg / mL PCBM. Fig.11c The cross-sectional morphology of the photoelectric sensor when the perovskite layer was annealed using a CB solution of 15 mg / mL P3HT & 15 mg / mL PCBM. Figures 11a to 11c It can be seen that when the perovskite layer is annealed using a CB solution containing 15 mg / mL P3HT & 15 mg / mL PCBM, part of the pinhole structure on the surface of the perovskite layer can be completely filled with the organic heterojunction material. The content of the organic heterojunction material in the perovskite layer is relatively high, and no second organic auxiliary layer is formed, which can effectively reduce the dark current of the photoelectric sensor. The comparison of the dark current is shown in the figure below. Figure 5 shown.

[0094] Fig.12a and Figure 12b The surface morphology of the photoelectric sensor when the perovskite layer was annealed using a CB solution of 50 mg / mL P3HT & 50 mg / mL PCBM. Fig.12c The cross-sectional morphology of the photoelectric sensor when the perovskite layer was annealed using a CB solution of 50 mg / mL P3HT & 50 mg / mL PCBM. Figures 12a to 12c It can be seen that when the perovskite layer is annealed using a CB solution of 50 mg / mL P3HT & 50 mg / mL PCBM, part of the pinhole structure on the surface of the perovskite layer can be completely filled with the organic heterojunction material. The content of organic heterojunction material in the perovskite layer is relatively high, and an obvious second organic auxiliary layer will be formed, which can passivate the perovskite surface, thereby further effectively reducing the dark current of the photoelectric sensor. The comparison of the dark current is shown in the figure below. Figure 5 shown.

[0095] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present disclosure, but the present disclosure is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and substance of the present disclosure, and these modifications and improvements are also considered to be within the scope of protection of the present disclosure.

Claims

1. A method for preparing a photoelectric sensor, characterized in that: The preparation method of the photoelectric sensor comprises: forming a first electrode on a substrate; A perovskite layer is formed on the first electrode; gaps are formed between perovskite grains on a side of the perovskite layer facing away from the substrate; annealing the perovskite layer using a first organic heterojunction material solution as an anti-solvent to form a first organic auxiliary layer; forming a second electrode on the first organic auxiliary layer; Before forming a second electrode on the first organic auxiliary layer, the method further comprises: The perovskite layer is annealed using a second organic heterojunction material solution as an anti-solvent to form a second organic auxiliary layer; wherein the concentration of the second organic heterojunction material solution is greater than the concentration of the first organic heterojunction material solution.

2. The method for preparing a photoelectric sensor according to claim 1, characterized in that: The solvents of the first organic heterojunction material solution and the second organic heterojunction material solution both include: chlorobenzene; The solutes of the first organic heterojunction material solution and the second organic heterojunction material solution both include: a donor material and an acceptor material.

3. The method for preparing a photoelectric sensor according to claim 2, characterized in that: The donor material includes: a macromolecular organic donor material; The receptor material includes: small molecule organic receptor material.

4. The method for preparing a photoelectric sensor according to claim 2, characterized in that: The concentration of the first organic heterojunction material solution is less than or equal to 30 mg / mL; The concentration of the second organic heterojunction material solution is greater than 30 mg / mL and less than or equal to 100 mg / mL.

5. A photoelectric sensor, prepared by the method for preparing a photoelectric sensor according to any one of claims 1 to 4, characterized in that: The photoelectric sensor comprises: a substrate, a first electrode and a second electrode located on the substrate and arranged opposite to each other, and a photosensitive layer located between the first electrode and the second electrode; The photosensitive layer includes: a perovskite layer; gaps are formed between the perovskite grains on the side of the perovskite layer away from the substrate; the photosensitive layer also includes: a first organic auxiliary layer; The first organic auxiliary layer includes: a first organic heterojunction material, and the first organic auxiliary layer is filled in the gaps between the perovskite grains.

6. The photoelectric sensor according to claim 5, characterized in that: The photosensitive layer further includes: a second organic auxiliary layer; The second organic auxiliary layer includes: a second organic heterojunction material, and the second organic auxiliary layer is located on a side of the first organic auxiliary layer away from the substrate.

7. The photoelectric sensor according to claim 6, characterized in that: The first organic heterojunction material is the same as the second organic heterojunction material.

8. The photoelectric sensor according to claim 6, characterized in that: The thickness of the first organic auxiliary layer is less than or equal to the gap depth between the perovskite grains in the perovskite layer; The thickness of the second organic auxiliary layer is less than or equal to the thickness of the perovskite layer.

9. The photoelectric sensor according to any one of claims 5 to 8, characterized in that: The doping ratio of the organic heterojunction material in the perovskite layer is 1 wt % to 30 wt %.

10. The photoelectric sensor according to any one of claims 5 to 8, characterized in that: The organic heterojunction material comprises: a donor material and an acceptor material; The mass of the donor material is equal to the mass of the acceptor material.

11. The photoelectric sensor according to claim 10, characterized in that: The donor material includes: a macromolecular organic donor material; The receptor material includes: small molecule organic receptor material.

12. The photoelectric sensor according to any one of claims 5 to 8, characterized in that: The photoelectric sensor further comprises: a hole transport layer and an electron transport layer; The hole transport layer is located on a side of the first electrode close to the perovskite layer; The electron transport layer is located on a side of the second electrode close to the perovskite layer.

13. A display device, characterized in that: The display device comprises: a plurality of display devices and a plurality of photoelectric sensors according to any one of claims 5 to 12; The photosensor is located between at least part of the adjacent display devices.

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