A lead sulfide quantum dot optoelectronic device and a preparation method thereof

Abstract

The application discloses a lead sulfide quantum dot photoelectric device and a preparation method thereof. The hole transport layer of the photoelectric device is a three-layer structure, a lower interface modification layer is a lead sulfide quantum dot film of a thiol small molecule ligand formed on a lower surface of a P-type organic polymer layer, and an upper interface modification layer is a three five-fluorophenyl boron doped poly[bis(4-phenyl)(2,4,6-trimethylphenyl) amine] film formed on an upper surface of the P-type organic polymer layer. The application forms a stable ohmic contact between a plurality of P-type polymer hole transport layers and a gold electrode by using the thiol small molecule modified PbS quantum dot transition organic / inorganic interface and the three five-fluorophenyl boron doped poly[bis(4-phenyl)(2,4,6-trimethylphenyl) amine] as a universal material for eliminating the barrier with the gold electrode, effectively blocks water and oxygen in the air from corroding the lead sulfide quantum dots, and significantly improves the efficiency and working stability of the lead sulfide quantum dot photoelectric device.

Description

TECHNICAL FIELD

[0001] The application relates to a lead sulfide quantum dot photoelectric device and a preparation method thereof, and belongs to the technical field of solar photovoltaics. BACKGROUND

[0002] Solar cells have had a research history of nearly 70 years. On the basis of the mature single-junction solar cell technology, stacked cells have rapidly developed in recent years. The stacked cells can combine multiple solar cells to achieve full coverage of the solar spectrum, thereby achieving a photoelectric conversion efficiency far exceeding that of single-junction solar cells. Among them, lead sulfide quantum dots, as a typical strong quantum confinement effect material, have attracted widespread attention in basic research and applied research. Because the band gap of the bulk material is very narrow (0.41 eV), the band gap of PbS quantum dots can cover the near-infrared to short-wave infrared band through size control, and the material can be processed at low cost through a solution method, so it is a relatively ideal new type of infrared semiconductor material. The recently developed quantum dot semiconductor ink preparation technology can greatly reduce the preparation cost of the material and simplify the device preparation process, so that the PbS quantum dot photoelectric application has gone from the laboratory to industrialization, showing great application potential.

[0003] With the year-by-year improvement of the power conversion efficiency (PCE) of PbS CQD solar cells, the stability of the devices has always been a concern. The prior art significantly improves the air stability of PbS CQD solar cells by successfully designing an ITO / zinc oxide (ZnO) / iodine-encapsulated PbS CQD / ethanedithiol (EDT)-encapsulated PbS CQD / gold device structure (see document: Nat. Mater. 2014, 13, 796). Subsequently, almost all PbS CQD solar cells have adopted this efficient N-I-P device structure. Recently, a P-type organic polymer has been used to replace PbS-EDT as a new hole transport layer (HTL) to further improve the hole extraction capability (see documents: Nat. Energy 2019, 4, 969, Adv. Mater. 2020, 32, 2004985, Adv. Energy Mater. 2021, 12, 2102689). These organic polymers are compatible with large-area single-film processes and are expected to become more efficient hole transport layer materials for the next generation of CQD solar cells.

[0004] Although a large number of literatures emphasize the excellent air stability of quantum dot solar cells, the working stability, which is more critical for practical application, has limited attention. In the widely used N-I-P device structure, the stability of the hole transport layer directly exposed to the external environment has a great influence on the stability of the device. The currently widely used PbS-EDT hole transport layer is easily oxidized under light conditions, resulting in a decrease in device performance. Currently, for PbS CQD solar cells based on organic HTL, the maximum power point (MPP) T 90 (time for the device efficiency to decay to 90% of the initial value) of the most stable device reported is 120 hours (see document: Adv. Energy Mater. 2021, 12, 2102689), while in devices based on inorganic HTL, the best T 90 is 260 hours (see document: Solar RRL 2022, 6, 2200488), which greatly hinders the practical application of the device. More and more studies have shown that the interface has a significant influence on the performance and stability of optoelectronic devices, especially in lead sulfide quantum dot optoelectronic devices, which needs to be further solved. SUMMARY

[0005] The present application aims at the low interface contact and working stability of the prior art lead sulfide quantum dot optoelectronic device, and provides a lead sulfide quantum dot optoelectronic device structure and a preparation method thereof, which can effectively improve the efficiency and working stability.

[0006] The technical scheme for achieving the object of the present application is to provide a lead sulfide quantum dot optoelectronic device, which comprises a conductive glass substrate, an electron transport layer, a quantum dot active layer, a hole transport layer and an electrode; the hole transport layer is a three-layer structure hole transport modification layer, comprising a lower interface modification layer, a P-type organic polymer layer and an upper interface modification layer; the lower interface modification layer is a lead sulfide quantum dot film formed by a thiol small molecule ligand on the lower surface of the P-type organic polymer layer, the size of the quantum dot is 3-10 nanometers, and the thickness of the film is 3-20 nanometers; the upper interface modification layer is a thin film of tris-pentafluorophenylboron doped poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] formed on the upper surface of the P-type organic polymer layer, the mass ratio of tris-pentafluorophenylboron to poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] is 1:20-1:4, and the thickness of the film is 5-30 nanometers.

[0007] The quantum dot active layer of the present application is a lead sulfide quantum dot film with a thickness of 100-800 nanometers; the size of the lead sulfide quantum dot is 3-10 nanometers; and the electron transport layer is one of SnO2 or ZnO thin films with a thickness of 10-200 nanometers.

[0008] The P-type organic polymer layer is one of poly(3-hexylthiophene-2,5-diyl), P5TCN-2F, P5TCN-F25, PBDB-T, and PM6 thin film; and the mass ratio of the trifluorophenyl boron to poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] in the upper interface modification layer is 1:10-1:4.

[0009] The photoelectric device includes a solar cell, an LED device, and a light detector.

[0010] The technical scheme further includes a preparation method of the lead sulfide quantum dot photoelectric device, and the steps are as follows:

[0011] (1) spin-coating an electron transport material on a conductive glass substrate to obtain an electron transport layer;

[0012] (2) preparing a lead sulfide quantum dot active layer on the electron transport layer;

[0013] (3) preparing a three-layer structure of a hole transport modification layer, including a lower interface modification layer, a P-type organic polymer layer, and an upper interface modification layer;

[0014] (a) preparing the lower interface modification layer: spin-coating the oleic acid-wrapped lead sulfide quantum dots on the quantum dot active layer and performing solid-state ligand exchange, the size of the quantum dots is 3-10 nanometers, and a lower interface modification layer with a film thickness of 3-20 nanometers is obtained;

[0015] (b) preparing the P-type organic polymer layer: spin-coating the P-type organic polymer solution on the lower interface modification layer to obtain a P-type organic polymer film, and then performing annealing treatment at a temperature of 30-70 ℃ for 1-10 minutes to obtain a P-type organic polymer layer with a film thickness of 10-200 nanometers;

[0016] (c) preparing the upper interface modification layer: according to the mass ratio of trifluorophenyl boron to poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] of 1:20-1:4, the trifluorophenyl boron-doped poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] is spread on the upper surface of the P-type organic polymer layer after annealing treatment, and after spin-drying, an upper interface modification layer with a film thickness of 5-30 nanometers is obtained;

[0017] (4) evaporating a gold electrode on the upper interface modification layer of the hole transport modification layer prepared in step (3) to obtain a lead sulfide quantum dot photoelectric device.

[0018] The preparation of the lower interface modification layer of the application dissolves the oleic acid-wrapped lead sulfide quantum dots in a non-polar solvent to obtain a solution, which is spin-coated on a quantum dot active layer to form a quantum dot film, wherein the non-polar solvent comprises one of n-hexane or n-octane; a thiol small molecule is diluted in a solvent at a volume ratio of 1:10000-1:10 to cover the surface of the quantum dot film for solid-state ligand exchange, and then washed and spin-dried to obtain the lower interface modification layer; the thiol small molecule comprises one of EDT or MPA, and the solvent comprises one of methanol or isopropanol.

[0019] The principle of the application is: through introducing a thiol molecular exchange lead sulfide quantum dot layer at the lower interface of the P-type organic polymer layer and a tris(pentafluorophenyl)boron-doped poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] layer at the upper interface, double interface processing is performed. Taking a poly(3-hexylthiophene-2,5-diyl) hole transport layer as an example, the efficiency is very low without an interface layer, and after introducing the interface layer, on the one hand, the lower interface layer can serve as an effective transition layer between the all-inorganic halogen passivated PbS quantum dot active layer and the organic polymer, and on the other hand, the tris(pentafluorophenyl)boron-doped poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] helps to form a stable ohmic contact between the poly(3-hexylthiophene-2,5-diyl) and the gold electrode, reducing the potential barrier between the poly(3-hexylthiophene-2,5-diyl) and the gold electrode; at the same time, the doping improves the mobility of the poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine], speeds up the carrier transport, and also effectively blocks water and oxygen, preventing the quantum dots from being excessively oxidized, and further improving the working stability of the lead sulfide quantum dot optoelectronic device. The double interface layer realizes good contact by promoting the surface energy conversion between different layers.

[0020] Compared with the prior art, the technical scheme provided by the application has the following advantages:

[0021] 1. The optoelectronic device provided by the application adopts a three-layer structure of the hole transport modification layer, which cooperatively realizes excellent extraction and transmission of holes from the quantum dot active layer to the gold electrode, and the tris(pentafluorophenyl)boron-doped poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] not only effectively blocks water and oxygen, but also constructs a stable ohmic contact between various P-type organic polymers and the gold electrode.

[0022] 2. The application provides a lead sulfide quantum dot optoelectronic device structure with a double interface layer, which realizes stable ohmic contact between various organic polymers and the gold electrode; unlike the generally expensive and difficult-to-synthesize polymers, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] as a typical commercial organic polymer material has high cost-effectiveness and is expected to be used for large-scale manufacturing.

[0023] 3. The surface treatment process provided by the application has wide applicability and is suitable for various P-type organic polymer hole transport layers; the process realizes the dual improvement of device efficiency and working stability.

[0024] 4. The technical scheme provided by the application relates to the technical field of photoelectric device preparation, and can be applied not only to lead sulfide quantum dot solar cells but also to lead sulfide quantum dot LED devices, light detectors and the like. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 A structure schematic diagram of the lead sulfide quantum dot photoelectric device solar cell provided by the application is shown in the figure;

[0026] Figure 1 In the figure, 1 is a conductive glass substrate, 2 is an electron transport layer, 3 is a lead sulfide active layer, 4 is a hole transport modification layer, and 5 is a gold electrode.

[0027] Figure 2 A structure schematic diagram of the hole transport modification layer provided by the embodiment of the application is shown in the figure;

[0028] Figure 2 In the figure, 4-1 is a lower interface modification layer, 4-2 is a P-type organic polymer layer, and 4-3 is an upper interface modification layer.

[0029] Figure 3 An interface scanning electron microscope image of the lead sulfide quantum dot solar cell prepared in the embodiment 1 of the application is shown in the figure;

[0030] Figure 4 A solution concentration and device efficiency broken line graph of poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] corresponding to the lead sulfide quantum dot solar cell prepared in the embodiment 1 of the application is shown in the figure;

[0031] Figure 5 A current density-voltage (J-V) curve graph of the lead sulfide quantum dot solar cell prepared in the embodiment 1 of the application is shown in the figure;

[0032] Figure 6 An air operation stability curve graph of the lead sulfide quantum dot solar cell prepared in the embodiment 1 of the application under continuous light irradiation is shown in the figure;

[0033] Figure 7 A current density-voltage (J-V) curve graph of the lead sulfide quantum dot solar cell prepared in the embodiment 2 of the application is shown in the figure;

[0034] Figure 8 A current density-voltage (J-V) curve graph of the lead sulfide quantum dot solar cell prepared in the embodiment 3 of the application is shown in the figure;

[0035] Figure 9 The current density-voltage (JV) curve of the lead sulfide quantum dot solar cell prepared in Example 4 of the present invention is shown.

[0036] Figure 10 The current density-voltage (JV) curve is shown for the lead sulfide quantum dot solar cell prepared in Example 5 of this invention. Detailed Implementation

[0037] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments. Example 1

[0038] This embodiment provides a lead sulfide quantum dot optoelectronic device, taking a solar cell as an example.

[0039] See appendix Figure 1 , 2 These are schematic diagrams of the lead sulfide quantum dot solar cell and the hole transport modification layer provided in this embodiment. Figure 1 The device structure shown is as follows: an electron transport layer 2, a lead sulfide quantum dot active layer 3, a hole transport modification layer 4, and a gold electrode 5 are sequentially fabricated on a conductive glass substrate 1. Figure 2 The hole transport modification layer structure shown is as follows: an upper interface modification layer 4-3 and a lower interface modification layer 4-1 are formed on the upper and lower surfaces of the P-type organic polymer layer 4-2, respectively.

[0040] This embodiment provides a lead sulfide quantum dot solar cell, and the specific steps for its fabrication are as follows:

[0041] Step 1: Spin-coat a ZnO thin film with a thickness of about 80 nanometers onto a clean indium tin oxide (ITO) conductive glass substrate to obtain an electron transport layer;

[0042] Step 2: In a nitrogen glove box, on the basis of the electron transport layer, spin-coat a lead sulfide quantum dot solution at 2000 rpm for 15 seconds to obtain a lead sulfide quantum dot light absorption layer with a thickness of about 400 nanometers, and anneal at 70°C for 10 minutes.

[0043] Step 3: Prepare a lead sulfide quantum dot lower interface layer with MPA ligands on the lead sulfide quantum dot light-absorbing layer. The specific method is as follows: Dissolve oleic acid-encapsulated lead sulfide quantum dots in n-octane to prepare a solution with a concentration of 5 mg / mL. Spin-coat at 2500 rpm for 20 seconds to form a quantum dot film approximately 7 nm thick. Then, soak the film in a methanol solution of MPA (volume ratio 1:500) for 30 seconds, wash with methanol, and spin dry to obtain the lower interface layer.

[0044] Step four, spin-coating to prepare P-type organic polymer layer on the lower interface layer. The specific method is: poly (3-hexylthiophene-2, 5-diyl) is dissolved in chlorobenzene to prepare a solution with a concentration of 6 mg / ml, spin-coating at 3000 rpm for 20 seconds to form a P-type organic polymer film with a thickness of about 20 nm, and then annealing at 50°C for 5 minutes to obtain the P-type organic polymer layer.

[0045] Step five, spin-coating to prepare the upper interface layer on the P-type organic polymer layer. The specific method is: poly [bis (4-phenyl) (2, 4, 6-trimethylphenyl) amine] is dissolved in toluene to prepare a solution with a concentration of 3 mg / ml, doped with 15% of triphenylphosphine borane, spin-coating at 3000 rpm for 40 seconds to form a thin film with a thickness of about 8 nm, and then obtaining the upper interface layer.

[0046] Step six, vacuum thermal evaporation of gold electrode with a thickness of 80 nm on the upper interface layer to obtain the lead sulfide quantum dot solar cell.

[0047] Referring to Fig. 5, it is an interface scanning electron microscope image of the lead sulfide quantum dot solar cell provided in this embodiment. Figure 3

[0048] According to the technical solution of this embodiment, the solution concentration of poly [bis (4-phenyl) (2, 4, 6-trimethylphenyl) amine] dissolved in toluene in step five is 1, 2, 4 and 5 mg / ml respectively, and the lead sulfide quantum dot solar cell is prepared.

[0049] Referring to Fig. 6, it is a solution concentration and device efficiency fold line graph of the lead sulfide quantum dot solar cell prepared in this embodiment corresponding to different poly [bis (4-phenyl) (2, 4, 6-trimethylphenyl) amine]. Figure 4 As can be seen from the figure, the optimal concentration is 3 mg / ml. Figure 4

[0050] Referring to Fig. 7, it is a current density-voltage (J-V) curve of the lead sulfide quantum dot solar cell provided in this embodiment, which uses lead sulfide quantum dots as light absorption layer, lead sulfide with MPA ligand as lower interface modification layer, poly (3-hexylthiophene-2, 5-diyl) as hole transport layer, and poly [bis (4-phenyl) (2, 4, 6-trimethylphenyl) amine] as upper interface modification layer. 2 Under the standard test conditions of AM 1.5G, 100 mW / cm 2 , the short-circuit current density of the device is measured to be 29.45 mA / cm 2 , the open-circuit voltage is 0.67 V, the fill factor is 71.77%, and the photoelectric conversion efficiency is 14.16%. Figure 5 Referring to Fig. 8, it is a current density-voltage (J-V) curve of the lead sulfide quantum dot solar cell provided in this embodiment, which uses lead sulfide quantum dots as light absorption layer, lead sulfide with MPA ligand as lower interface modification layer, poly (3-hexylthiophene-2, 5-diyl) as hole transport layer, and poly [bis (4-phenyl) (2, 4, 6-trimethylphenyl) amine] as upper interface modification layer. Figure 6 ​​It is a stability curve diagram of the lead sulfide quantum dot solar cell provided in the embodiment under AM1.5G continuous light in the air, the air humidity is about 45%, the device surface temperature is about 50℃, and the efficiency of the unsealed device can still maintain 90% of the original efficiency after about 520 hours. Embodiment 2

[0052] The embodiment provides a lead sulfide quantum dot solar cell, and the structure is shown in the accompanying drawings. Figure 1 and the accompanying drawings. Figure 2 The preparation of the cell includes the following steps: sequentially preparing an electron transport layer, a lead sulfide quantum dot light absorption layer, a lower interface layer, a P-type organic polymer layer, an upper interface layer and a gold electrode on a conductive glass substrate. The specific steps are as follows:

[0053] Step one: spin coating a layer of ZnO film with a thickness of about 80 nanometers on a clean indium tin oxide (ITO for short) conductive glass substrate to obtain an electron transport layer;

[0054] Step two: in a nitrogen glove box, spin coating a lead sulfide quantum dot solution on the basis of the electron transport layer at 2000 revolutions per minute for 15 seconds to obtain a lead sulfide quantum dot light absorption layer with a thickness of about 400 nanometers, and annealing at 70℃ for 10 minutes.

[0055] Step three: preparing a lower interface layer of the lead sulfide quantum dot with MPA ligand on the lead sulfide quantum dot light absorption layer. The specific method is as follows: dissolving the lead sulfide quantum dot wrapped with oleic acid in n-octane to prepare a solution with a concentration of 5 milligrams per milliliter, spin coating at a speed of 2500 revolutions per minute for 20 seconds to form a quantum dot layer with a thickness of about 7 nanometers, then immersing in a methanol solution of MPA (volume ratio is 1:500) for 30 seconds, washing with methanol and spin-drying to obtain the lower interface layer.

[0056] Step four: spin coating a P-type organic polymer layer on the lower interface layer. The specific method is as follows: dissolving P5TCN-2F in chlorobenzene to prepare a solution with a concentration of 6 milligrams per milliliter, spin coating at a speed of 3000 revolutions per minute for 20 seconds to form a P-type organic polymer layer with a thickness of about 20 nanometers, and annealing at 50℃ for 5 minutes.

[0057] Step five: spin coating an upper interface layer on the P-type organic polymer layer. The specific method is as follows: dissolving poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] in toluene to prepare a solution with a concentration of 3 milligrams per milliliter, doping 15% of tri(pentafluorophenyl)borane by mass fraction, spin coating at a speed of 3000 revolutions per minute for 40 seconds to form an upper interface layer with a thickness of about 8 nanometers.

[0058] Step six: vacuum thermal evaporation of a gold electrode with a thickness of 80 nanometers on the upper interface layer to obtain a lead sulfide quantum dot solar cell.

[0059] See appendix Figure 7 This embodiment presents the current density-voltage (JV) curve of a lead sulfide quantum dot solar cell using lead sulfide quantum dots as the light absorption layer, lead sulfide with MPA ligands as the lower interface modification layer, P5TCN-2F as the p-type organic polymer layer, and poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] as the upper interface modification layer. At AM1.5G and 100 mW / cm², [the voltage is measured in JV]. 2 Under standard test conditions, the measured short-circuit current density of the device was 27.19 mA / cm². 2 The open-circuit voltage is 0.67 V, the fill factor is 68.64%, and the photoelectric conversion efficiency is 12.50%. Example 3

[0060] This embodiment provides a lead sulfide quantum dot solar cell, the structure of which is shown in the attached figure. Figure 1 and attached Figure 2 As shown, the battery fabrication includes the following steps: sequentially fabricating an electron transport layer, a lead sulfide quantum dot light absorption layer, a lower interface layer, a p-type organic polymer layer, an upper interface layer, and a gold electrode on a conductive glass substrate. The specific fabrication steps are as follows:

[0061] Step 1: Spin-coat a ZnO thin film with a thickness of about 80 nanometers onto a clean indium tin oxide (ITO) conductive glass substrate to obtain an electron transport layer;

[0062] Step 2: In a nitrogen glove box, on the basis of the electron transport layer, spin-coat a lead sulfide quantum dot solution at 2000 rpm for 15 seconds to obtain a lead sulfide quantum dot light absorption layer with a thickness of about 400 nanometers, and anneal at 70°C for 10 minutes.

[0063] Step 3: Prepare a lead sulfide quantum dot lower interface layer with MPA ligands on the lead sulfide quantum dot light-absorbing layer. The specific method is as follows: Dissolve oleic acid-encapsulated lead sulfide quantum dots in n-octane to prepare a solution with a concentration of 5 mg / mL. Spin-coat the solution at 2500 rpm for 20 seconds to form a quantum dot layer approximately 7 nm thick. Then, soak the layer in a methanol solution of MPA (volume ratio 1:500) for 30 seconds, wash with methanol, and spin-dry to obtain the lower interface layer.

[0064] Step 4: Spin-coat a P-type organic polymer layer onto the lower interface layer. The specific method is as follows: Dissolve P5TCN-F25 in chlorobenzene to prepare a solution with a concentration of 6 mg / mL. Spin-coat at 3000 rpm for 20 seconds to form a P-type organic polymer layer with a thickness of approximately 20 nm. Then anneal at 50°C for 5 minutes.

[0065] Step 5: Spin-coat an interface layer onto the P-type organic polymer layer. The specific method is as follows: Dissolve poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] in toluene to prepare a solution with a concentration of 3 mg / mL, dop with 15% by mass of tris(pentafluorophenylborane), spin-coat at 3000 rpm for 40 seconds to form an upper interface layer with a thickness of approximately 8 nanometers.

[0066] Step six: Vacuum thermally deposit an 80-nanometer-thick gold electrode on the upper interface layer to obtain a lead sulfide quantum dot solar cell.

[0067] See appendix Figure 8 This embodiment presents a current density-voltage (JV) curve for a lead sulfide quantum dot solar cell using lead sulfide quantum dots as the light-absorbing layer, lead sulfide with MPA ligands as the lower interface modification layer, P5TCN-F25 as the p-type organic polymer layer, and poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] as the upper interface modification layer. The curve is shown at AM1.5G and 100 mW / cm². 2 Under standard test conditions, the measured short-circuit current density of the device was 27.10 mA / cm². 2 The open-circuit voltage is 0.67 V, the fill factor is 69.24%, and the photoelectric conversion efficiency is 12.57%. Example 4

[0068] This embodiment provides a lead sulfide quantum dot solar cell, the structure of which is shown in the attached figure. Figure 1 and attached Figure 2 As shown, the battery fabrication includes the following steps: sequentially fabricating an electron transport layer, a lead sulfide quantum dot light absorption layer, a lower interface layer, a p-type organic polymer layer, an upper interface layer, and a gold electrode on a conductive glass substrate. The specific fabrication steps are as follows:

[0069] Step 1: Spin-coat a ZnO thin film with a thickness of about 80 nanometers onto a clean indium tin oxide (ITO) conductive glass substrate to obtain an electron transport layer;

[0070] Step 2: In a nitrogen glove box, on the basis of the electron transport layer, spin-coat a lead sulfide quantum dot solution at 2000 rpm for 15 seconds to obtain a lead sulfide quantum dot light absorption layer with a thickness of about 400 nanometers, and anneal at 70°C for 10 minutes.

[0071] Step 3: Prepare a lead sulfide quantum dot lower interface layer with MPA ligands on the lead sulfide quantum dot light-absorbing layer. The specific method is as follows: Dissolve oleic acid-encapsulated lead sulfide quantum dots in n-octane to prepare a solution with a concentration of 5 mg / mL. Spin-coat the solution at 2500 rpm for 20 seconds to form a quantum dot layer approximately 7 nm thick. Then, soak the layer in a methanol solution of MPA (volume ratio 1:500) for 30 seconds, wash with methanol, and spin-dry to obtain the lower interface layer.

[0072] Step 4: Spin-coat a P-type organic polymer layer onto the lower interface layer. The specific method is as follows: Dissolve PBDB-T in chlorobenzene to prepare a solution with a concentration of 6 mg / mL. Spin-coat at 3000 rpm for 20 seconds to form a P-type organic polymer layer with a thickness of approximately 20 nm. Then anneal at 50°C for 5 minutes.

[0073] Step 5: Spin-coat an interface layer onto the P-type organic polymer layer. The specific method is as follows: Dissolve poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] in toluene to prepare a solution with a concentration of 3 mg / mL, dop with 15% by mass of tris(pentafluorophenylborane), spin-coat at 3000 rpm for 40 seconds to form an upper interface layer with a thickness of approximately 8 nanometers.

[0074] Step six: Vacuum thermally deposit an 80-nanometer-thick gold electrode on the upper interface layer to obtain a lead sulfide quantum dot solar cell.

[0075] See appendix Figure 9 This embodiment presents a current density-voltage (JV) curve for a lead sulfide quantum dot solar cell using lead sulfide quantum dots as the light-absorbing layer, lead sulfide with MPA ligands as the lower interface modification layer, PBDB-T as the p-type organic polymer layer, and poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] as the upper interface modification layer. The curve is shown at AM1.5G and 100 mW / cm². 2 Under standard test conditions, the measured short-circuit current density of the device was 26.53 mA / cm². 2 The open-circuit voltage is 0.68 V, the fill factor is 65.70%, and the photoelectric conversion efficiency is 11.85%. Example 5

[0076] This embodiment provides a lead sulfide quantum dot solar cell, the structure of which is shown in the attached figure. Figure 1 and attached Figure 2 As shown, the battery fabrication includes the following steps: sequentially fabricating an electron transport layer, a lead sulfide quantum dot light absorption layer, a lower interface layer, a p-type organic polymer layer, an upper interface layer, and a gold electrode on a conductive glass substrate. The specific fabrication steps are as follows:

[0077] Step one, spin-coat a layer of ZnO film with a thickness of about 80 nanometers on a clean indium tin oxide (ITO) conductive glass substrate to obtain an electron transport layer;

[0078] Step two, in a nitrogen glove box, spin-coat a lead sulfide quantum dot solution on the basis of the electron transport layer at 2000 revolutions per minute for 15 seconds to obtain a lead sulfide quantum dot light absorption layer with a thickness of about 400 nanometers, and anneal at 70°C for 10 minutes.

[0079] Step three, prepare a lower interface layer of MPA ligand coated lead sulfide quantum dots on the lead sulfide quantum dot light absorption layer. The specific method is as follows: dissolve the oleic acid coated lead sulfide quantum dots in n-octane to prepare a solution with a concentration of 5 milligrams per milliliter, spin-coat at a speed of 2500 revolutions per minute for 20 seconds to form a quantum dot layer with a thickness of about 7 nanometers, then immerse in a methanol solution of MPA (volume ratio of 1:500) for 30 seconds, wash with methanol and spin-dry to obtain the lower interface layer.

[0080] Step four, spin-coat a P-type organic polymer layer on the lower interface layer. The specific method is as follows: dissolve PM6 in chlorobenzene to prepare a solution with a concentration of 6 milligrams per milliliter, spin-coat at a speed of 3000 revolutions per minute for 20 seconds to form a P-type organic polymer layer with a thickness of about 20 nanometers, and anneal at 50°C for 5 minutes.

[0081] Step five, spin-coat an upper interface layer on the P-type organic polymer layer. The specific method is as follows: dissolve poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] in toluene to prepare a solution with a concentration of 3 milligrams per milliliter, dope with 15% mass fraction of tri(pentafluorophenyl)borane, spin-coat at a speed of 3000 revolutions per minute for 40 seconds to form an upper interface layer with a thickness of about 8 nanometers.

[0082] Step six, vacuum thermal evaporate a gold electrode with a thickness of 80 nanometers on the upper interface layer to obtain a lead sulfide quantum dot solar cell.

[0083] Referring to FIG. 1, Figure 10 which is the current density-voltage (J-V) curve of the lead sulfide quantum dot solar cell provided in the embodiment, using lead sulfide quantum dots as the light absorption layer, MPA ligand coated lead sulfide as the lower interface modification layer, PM6 as the P-type organic polymer layer, and poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] as the upper interface modification layer; under standard test conditions of AM 1.5G, 100 mW / cm 2 , the short-circuit current density of the device is measured to be 25.27 mA / cm 2 , the open-circuit voltage is 0.69 V, the fill factor is 58.26%, and the photoelectric conversion efficiency is 10.16%.

Claims

1. A lead sulfide quantum dot optoelectronic device comprising a conductive glass substrate, an electron transport layer, a lead sulfide quantum dot active layer, a hole transport layer, and an electrode, characterized in that: The hole transport layer is a three-layer structure hole transport modification layer, comprising a lower interface modification layer, a P-type organic polymer layer, and an upper interface modification layer; the lower interface modification layer is a lead sulfide quantum dot film of a thiol small molecule ligand formed on the lower surface of the P-type organic polymer layer, the size of the quantum dot is 3-10 nanometers, the film thickness is 3-20 nanometers, and the lower interface modification layer is in contact with the lead sulfide quantum dot active layer; the upper interface modification layer is a thin film of tris-pentafluorophenylboron doped poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] formed on the upper surface of the P-type organic polymer layer, and the mass ratio of tris-pentafluorophenylboron to poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] is 1:20-1:4, and the film thickness is 5-30 nanometers.

2. The lead sulfide quantum dot optoelectronic device of claim 1, wherein: In the upper interface modification layer, the mass ratio of tris-pentafluorophenylboron to poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] is 1:10-1:

4.

3. The lead sulfide quantum dot optoelectronic device of claim 1, wherein: The P-type organic polymer layer is one of poly(3-hexylthiophene-2,5-diyl), P5TCN-2F, P5TCN-F25, PBDB-T, and PM6 thin films.

4. The lead sulfide quantum dot optoelectronic device of claim 1, wherein: The quantum dot active layer is a lead sulfide quantum dot film with a thickness of 100-800 nanometers; the size of the lead sulfide quantum dot is 3-10 nanometers.

5. The lead sulfide quantum dot optoelectronic device of claim 1, wherein: The electron transport layer is one of SnO2 or ZnO thin films with a thickness of 10-200 nanometers.

6. The lead sulfide quantum dot optoelectronic device of claim 1, wherein: The photoelectric device includes a solar cell, an LED device, or a light detector.

7. A method for preparing a lead sulfide quantum dot optoelectronic device according to claim 1, characterized in that... The method comprises the following steps: (1) spin-coating an electron transport material on a conductive glass substrate to obtain an electron transport layer; (2) preparing a lead sulfide quantum dot active layer on the electron transport layer; (3) preparing a three-layer structure hole transport modification layer, comprising a lower interface modification layer, a P-type organic polymer layer, and an upper interface modification layer; (a) preparing the lower interface modification layer: spin-coating lead sulfide quantum dots wrapped with oleic acid on the quantum dot active layer and performing solid-state ligand exchange, the size of the quantum dot is 3-10 nanometers, to obtain a lower interface modification layer with a film thickness of 3-20 nanometers; (b) preparing the P-type organic polymer layer: spin-coating a P-type organic polymer solution on the lower interface modification layer to obtain a P-type organic polymer thin film, and then performing annealing treatment at a temperature of 30-70°C for 1-10 minutes to obtain a P-type organic polymer layer with a film thickness of 10-200 nanometers; (c) preparing the upper interface modification layer: tris-pentafluorophenylboron doped poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] is spread on the upper surface of the P-type organic polymer layer after annealing treatment according to a mass ratio of tris-pentafluorophenylboron to poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] of 1:20-1:4, and after spin-drying, an upper interface modification layer with a film thickness of 5-30 nanometers is obtained; (4) evaporating a gold electrode on the upper interface modification layer of the hole transport modification layer prepared in step (3) to obtain a lead sulfide quantum dot photoelectric device.

8. The method of claim 7, wherein the method further comprises: The preparation of the lower interface modification layer, dissolving the oleic acid-wrapped lead sulfide quantum dots in a non-polar solvent to obtain a solution, spin-coating the solution on a quantum dot active layer to form a quantum dot film, wherein the non-polar solvent comprises one of n-hexane or n-octane; diluting a thiol small molecule in a solvent at a volume ratio of 1:10000-1:10 to cover the surface of the quantum dot film for solid-state ligand exchange, and then washing and spin-drying to obtain the lower interface modification layer; wherein the thiol small molecule comprises one of EDT or MPA, and the solvent comprises one of methanol or isopropanol.

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