A photovoltaic device and a method of manufacturing the same
By modifying the PbS-PbX2 quantum dot layer with YbBr3 solution in photovoltaic devices, the surface defect problem was solved, photon utilization and carrier lifetime were improved, and efficient photovoltaic performance was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ANHUI LIANGXIN OPTOELECTRONICS TECHNOLOGY CO LTD
- Filing Date
- 2026-02-10
- Publication Date
- 2026-05-29
AI Technical Summary
Existing photovoltaic devices suffer from technical bottlenecks such as nonradiative recombination, light absorption instability, insufficient spectral utilization, and low carrier extraction efficiency caused by surface defects in the PbS quantum dot layer.
The PbS-PbX2 quantum dot layer was modified with YbBr3 solution to form Yb3+/Br- ion coordination bonds. The quantum cutting properties of Yb3+ were used to improve photon utilization, and surface defects were passivated by Yb3+/Br- to reduce surface trap density.
Significantly improves the short-circuit current and overall power conversion efficiency of photovoltaic devices, extends carrier lifetime, increases open-circuit voltage and fill factor, enhances device stability, and realizes broadband response and high-gain near-infrared photovoltaic devices.
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Figure CN122121407A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of photovoltaic device technology, specifically relating to a photovoltaic device and its preparation method. Background Technology
[0002] The efficient utilization of solar energy is key to solving energy and environmental problems, and the core of improving the performance of photovoltaic devices lies in the improvement of light-absorbing materials. As a narrow bandgap semiconductor material, PbS quantum dots can achieve bandgap tuning by controlling the size of 2~6nm, and can efficiently respond to near-infrared solar radiation, making them a key material for improving the spectral utilization of photovoltaic devices and showing significant application potential in the photovoltaic field.
[0003] Currently, hot-injection polymerization is the mainstream technique for synthesizing uniformly sized PbS quantum dots. However, the oleic acid ligands coated on the surface of the synthesized product hinder carrier transport and induce defect state recombination, affecting device performance. Existing technologies mostly use halogen (I) - / Br - The ligand liquid-phase exchange strategy replaces the oleic acid ligand and passivates the surface, effectively reducing the trapped state density and enabling PbS quantum dot-based photovoltaic devices to achieve a power conversion efficiency of over 10% at the 980nm absorption peak. However, such photovoltaic devices still suffer from technical bottlenecks such as nonradiative recombination caused by surface defects in the quantum dot layer, light absorption instability, insufficient spectral utilization, and low carrier extraction efficiency. Summary of the Invention
[0004] Therefore, the purpose of this invention is to provide a photovoltaic device and a method for its fabrication.
[0005] In a first aspect, the present invention provides a photovoltaic device comprising, from bottom to top: a substrate, an electron transport layer, a PbS-PbX2 quantum dot layer spin-coated with YbBr3, a PbS-EDT layer, and a metal layer, wherein X is Br and / or Cl.
[0006] Preferably, the substrate is an ITO glass substrate.
[0007] Preferably, the electron transport layer material is one of zinc oxide and tin oxide, and the thickness of the electron transport layer is 130~160nm.
[0008] Preferably, the thickness of the YbBr3-modified PbS-PbX2 quantum dot layer is 300~400 nm.
[0009] Preferably, the thickness of the PbS-EDT layer is 35~55nm.
[0010] Preferably, the thickness of the metal layer is one or more of Au, Ag, and Al; the thickness of the metal layer is 60~100 nm.
[0011] Secondly, the present invention provides a method for fabricating a photovoltaic device, comprising the following steps: S1: A solution of electron transport layer material is spin-coated onto a substrate to obtain an electron transport layer; S2: Spin-coat a PbS-PbX2 quantum dot solution onto the electron transport layer to obtain a PbS-PbX2 quantum dot layer; spin-coat a YbBr3 solution onto the PbS-PbX2 quantum dot layer, and anneal under an inert atmosphere to obtain a YbBr3 spin-coated modified PbS-PbX2 quantum dot layer. S3: Spin-coat PbS-OA quantum dot solution onto PbS-PbX2 quantum dot layer to obtain PbS-OA layer; then cover PbS-OA layer with EDT solution for ligand exchange, and after washing, obtain PbS-EDT layer. S4: A metal layer is deposited on the PbS-EDT layer to obtain a photovoltaic device.
[0012] Preferably, in step S1, the concentration of the electron transport layer material solution is 40~60 mg / L, the solvent is a mixed solvent composed of chloroform and methanol, and the volume ratio of chloroform to methanol is (0.5~1.5):(0.5~1.5); the spin coating speed is 4000~6000 rpm, and the spin coating time is 8~12 s.
[0013] Preferably, in step S2, the concentration of the PbS-PbX2 quantum dot solution is 120~180 mg / mL, and the solvent is n-butylamine.
[0014] Preferably, in step S2, the spin-coating speed of the PbS-PbX2 quantum dot solution is 1500~2000 rpm, and the spin-coating time of the PbS-PbX2 quantum dot solution is 8~12 s.
[0015] Preferably, in step S2, the concentration of the YbBr3 solution is 8~15 mg / mL, and the solvent is N,N-dimethylformamide.
[0016] Preferably, in step S2, the spin-coating speed of the YbBr3 solution is 4000~6000 rpm, the spin-coating time of the YbBr3 solution is 8~12 s, and 70~80 μL of YbBr3 solution is spin-coated per square centimeter of PbS-PbX2 quantum dot layer.
[0017] Preferably, in step S2, the annealing temperature is 75~80℃ and the annealing time is 8~12min.
[0018] Preferably, in step S3, the concentration of the PbS-OA quantum dot solution is 35~40 mg / mL, and the solvent is n-hexane; the solvent of the EDT solution is acetonitrile (ACN), and the concentration of the EDT solution is 0.01~0.03 wt%.
[0019] Preferably, in step S3, the inert atmosphere is a nitrogen atmosphere or an argon atmosphere.
[0020] Preferably, in step S3, the spin coating speed is 2000~3000 rpm, the spin coating time is 8~12s, and the ligand exchange time is 20~40s.
[0021] Preferably, in step S4, the vapor deposition is performed using vacuum vapor deposition.
[0022] Compared with the prior art, one or more of the above technical solutions can achieve at least one of the following beneficial effects: In the photovoltaic device of this invention, ytterbium bromide is spin-coated onto the surface of a PbS-PbX2 quantum dot layer that has undergone halogen ligand exchange, thereby enabling Yb 3+ / Br - Ionic coordination bonds are formed on the PbS surface; the first method is through the use of Yb 3+ The quantum cutting properties of Yb allow it to absorb high-energy visible light and emit two 980nm near-infrared photons, which are then absorbed again by adjacent PbS quantum dots, improving photon utilization and thus significantly increasing short-circuit current and overall power conversion efficiency. 3+ / Br - Surface passivation of vacancy defects reduces surface trap density, prolongs carrier lifetime, and improves open-circuit voltage and fill factor. Attached Figure Description
[0023] Figure 1 This is a process flow diagram of the preparation method of the present invention. Detailed Implementation
[0024] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.
[0025] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.
[0026] As mentioned above, in a first aspect, the present invention provides a photovoltaic device comprising, from bottom to top: a substrate, an electron transport layer, a PbS-PbX2 quantum dot layer spin-coated with YbBr3, a PbS-EDT layer, and a metal layer, wherein X is Br and / or Cl.
[0027] The optoelectronic device of the present invention has the following multiple effects by modifying the PbS-PbX2 quantum dot layer with YbBr3 solution: (1) The spectral utilization rate is greatly improved: with the help of Yb 3+ The quantum cutting characteristics convert the absorbed visible light into two 980nm near-infrared photons, achieving a gain in the number of photons absorbed, effectively increasing the short-circuit current of the device, and significantly improving the overall power conversion efficiency under the same illumination conditions. (2) Significant surface defect passivation effect: Yb 3+ / Br - Stable coordination bonds are formed with the surface of PbS-PbX2 quantum dots, which greatly reduces the surface trap density and extends the carrier lifetime, thereby achieving a dual improvement in device open-circuit voltage (Voc) and fill factor. (3) Enhanced device working stability: The efficient passivation of quantum dot surface defects significantly reduces the probability of nonradiative recombination, reduces energy loss, effectively extends the device lifespan, and ensures that the device can still maintain excellent photovoltaic performance after long-term illumination. (4) Multi-effect synergy to achieve gain superposition: The two core effects of surface passivation and quantum trimming play a role simultaneously in the same layer structure, and the photovoltaic gains generated are superimposed. The synergistic effect is far superior to the traditional technical solutions of simply improving the spectral response or simply performing surface passivation, and finally realizes the fabrication of broadband response, high gain, and low cost near-infrared photovoltaic devices.
[0028] Preferably, the substrate is an ITO glass substrate.
[0029] Preferably, the electron transport layer material is one of zinc oxide and tin oxide, and the thickness of the electron transport layer is 130~160nm, including but not limited to: 130nm, 140nm, 150nm, 160nm, etc.
[0030] Preferably, the thickness of the YbBr3-modified PbS-PbX2 quantum dot layer is 300~400nm, including but not limited to: 300nm, 320nm, 350nm, 380nm, 400nm, etc.
[0031] Preferably, the thickness of the PbS-EDT layer is 35~55nm, including but not limited to: 35nm, 40nm, 45nm, 50nm, 55nm, etc.
[0032] Preferably, the thickness of the metal layer is one or more of Au, Ag and Al; the thickness of the metal layer is 60~100nm, including but not limited to: 60nm, 70nm, 80nm, 90nm, 100nm, etc.
[0033] Secondly, the present invention provides a method for fabricating a photovoltaic device, comprising the following steps: S1: A solution of electron transport layer material is spin-coated onto a substrate to obtain an electron transport layer; S2: Spin-coat a PbS-PbX2 quantum dot solution onto the electron transport layer to obtain a PbS-PbX2 quantum dot layer; spin-coat a YbBr3 solution onto the PbS-PbX2 quantum dot layer, and anneal under an inert atmosphere to obtain a modified PbS-PbX2 quantum dot layer. S3: Spin-coat PbS-OA quantum dot solution onto PbS-PbX2 quantum dot layer to obtain PbS-OA layer; then cover PbS-OA layer with EDT solution for ligand exchange, and after washing, obtain PbS-EDT layer. S4: A metal layer is deposited on the PbS-EDT layer to obtain a photovoltaic device.
[0034] In the method of this invention, the annealing process is carried out entirely under an inert atmosphere, with a maximum temperature not exceeding 80°C. This method is compatible with large-area solution processing and offers advantages such as low cost and simple process. The annealing step is completed under an inert atmosphere, with a maximum heat treatment temperature not exceeding 80°C. The use of a solution spin-coating method facilitates large-area film formation, significantly reducing manufacturing costs while improving production efficiency.
[0035] Preferably, in step S1, the concentration of the electron transport layer material solution is 40~60 mg / L, including but not limited to: 40 mg / L, 45 mg / L, 50 mg / L, 55 mg / L, 60 mg / L, etc.; the solvent is a mixed solvent composed of chloroform and methanol, and the volume ratio of chloroform to methanol is (0.5~1.5):(0.5~1.5), including but not limited to: 0.5:1, 0.5:1.5, 1:1, 1:0.5, 1.5:1, 1.5:0.5, etc.; the spin coating speed is 4000~6000 rpm, including but not limited to: 4000 rpm, 4500 rpm, 5000 rpm, 5500 rpm, 6000 rpm, etc.; the spin coating time is 8~12 s, including but not limited to: 8s, 9s, 10s, 11s, 12s, etc.
[0036] Preferably, in step S2, the concentration of the PbS-PbX2 quantum dot solution is 120~180 mg / mL, including but not limited to: 120 mg / mL, 130 mg / mL, 140 mg / mL, 150 mg / mL, 160 mg / mL, 170 mg / mL, 180 mg / mL, etc.; the solvent is n-butylamine.
[0037] Preferably, in step S2, the spin-coating speed of the PbS-PbX2 quantum dot solution is 1500~2000 rpm, including but not limited to: 1500 rpm, 1600 rpm, 1700 rpm, 1800 rpm, 1900 rpm, 2000 rpm, etc.; the spin-coating time of the PbS-PbX2 quantum dot solution is 8~12s, including but not limited to: 8s, 9s, 10s, 11s, 12s, etc.
[0038] Preferably, in step S2, the concentration of the YbBr3 solution is 8~15 mg / mL, including but not limited to: 8 mg / mL, 9 mg / mL, 10 mg / mL, 11 mg / mL, 12 mg / mL, 13 mg / mL, 14 mg / mL, 15 mg / mL, etc.; the solvent is N,N-dimethylformamide.
[0039] Preferably, in step S2, the spin-coating speed of the YbBr3 solution is 4000~6000 rpm, including but not limited to: 4000 rpm, 4500 rpm, 5000 rpm, 5500 rpm, 6000 rpm, etc.; the spin-coating time of the YbBr3 solution is 8~12s, including but not limited to: 8s, 9s, 10s, 11s, 12s, etc.; when spin-coating the YbBr3 solution, 70~80μL (including but not limited to: 70μL, 72μL, 75μL, 78μL, 80μL, etc.) of YbBr3 solution is spin-coated per square centimeter of PbS-PbX2 quantum dot layer.
[0040] Preferably, in step S2, the annealing temperature is 75~80℃, including but not limited to: 75℃, 76℃, 77℃, 78℃, 79℃, 80℃, etc.; the annealing time is 8~12min, including but not limited to: 8min, 9min, 10min, 11min, 12min, etc.
[0041] Preferably, in step S3, the concentration of the PbS-OA quantum dot solution is 35~40 mg / mL, including but not limited to: 35 mg / mL, 36 mg / mL, 37 mg / mL, 38 mg / mL, 39 mg / mL, 40 mg / mL, etc.; the solvent is n-hexane; the solvent of the EDT solution is acetonitrile (ACN), and the concentration of the EDT solution is 0.01~0.03 wt%, including but not limited to: 0.01 wt%, 0.02 wt%, 0.03 wt%, etc.
[0042] Preferably, in step S3, the inert atmosphere is a nitrogen atmosphere or an argon atmosphere.
[0043] Preferably, in step S3, the spin coating speed is 2000~3000 rpm, including but not limited to: 2000 rpm, 2200 rpm, 2400 rpm, 2600 rpm, 2800 rpm, 3000 rpm, etc.; the spin coating time is 8~12s, including but not limited to: 8s, 9s, 10s, 11s, 12s, etc.; the ligand exchange time is 20~40s, including but not limited to: 20s, 25s, 30s, 35s, 40s, etc.
[0044] Preferably, vacuum evaporation is used in step S4.
[0045] Preparation Example 1: Preparation of PbS-OA quantum dots 4.5 g PbO, 16 mL OA (oleic acid), and 40 mL ODE (octadecene) were mixed and added to a reactor. The mixture was then heated to 80 °C under vacuum and maintained at this temperature for 1 hour. After the heat treatment, nitrogen gas was continuously purged into the flask for 8 minutes. After the purging was completed, a vacuum was applied, and the temperature was raised to 120 °C under vacuum, and the reaction was allowed to proceed for 40 minutes. Then, 11.4 mL of (TMS)2M (bis(trimethylsilyl)sulfide) ODE solution (1.4 mL of (TMS)2M dissolved in 10 mL of ODE and subjected to deoxygenation and dehydration treatment) was injected into the reaction solution. The reaction was allowed to proceed rapidly for 1 minute. Finally, 40 mL of ODE solution was injected... The reaction was quenched with mL of n-hexane, and the reaction solution was cooled to 0-2℃ in an ice bath. It was then allowed to stand at 0-2℃ for 12 h, followed by centrifugation at 6000 rpm for 5 min. Washing solution (ethyl acetate and ethanol in a volume ratio of 1:2) was added to the supernatant after centrifugation, and the mixture was shaken for 30 min. After centrifugation at 4000 rpm for 5 min, PbS-OA quantum dots precipitated out. The supernatant was poured off, and washing solution was added again. The washing process was repeated 3 times to obtain wet PbS-OA quantum dots. The wet PbS-OA quantum dots were then vacuum dried for 4 h to obtain PbS-OA quantum dots (the absorption peak of the quantum dots was 885 nm).
[0046] Preparation Example 2: Preparation of PbS-PbX2 quantum dots 0.922 g of PbI₂, 0.294 g of PbBr₂, and 0.0617 g of ammonium acetate were added to 20 mL of DMF. The solution was shaken at 50 °C for 3 h to allow the solutes to dissolve completely. The solution was then filtered through a polytetrafluoroethylene (PTFE) filter with a pore size of 0.22 μm, and the filtrate was the lead halide precursor solution. The PbS-OA quantum dots prepared in Preparation Example 1 were dispersed in n-hexane to prepare a 7 mg / mL PbS-OA quantum dot solution. 20 mL of the PbS-OA quantum dot solution was added to 20 mL of the lead halide precursor solution. After shaking at 50 °C for 3 min, the upper layer of liquid became colorless, and the lower layer of liquid became black. The upper layer of liquid was then poured off, and the lower layer of liquid was washed with n-hexane five times. Toluene was then added, and the mixture was centrifuged. The solid after centrifugation was then vacuum dried to obtain PbS-PbX₂ quantum dots.
[0047] The process flow diagram of the photovoltaic device fabrication method in this invention is shown below. Figure 1 The specific steps can be found in the embodiments.
[0048] Example 1 S1: After cleaning the ITO glass substrate, a cleaned ITO / glass substrate is obtained; zinc oxide nanoparticles are dispersed in a mixed solvent of chloroform and methanol with a volume ratio of 1:1 to prepare a zinc oxide solution with a concentration of 50 mg / L; the zinc oxide solution is spin-coated onto the ITO / glass substrate at a speed of 5000 rpm for 10 s, and the spin-coating is repeated twice to obtain a zinc oxide electron transport layer with a thickness of 150 nm.
[0049] S2: The PbS-PbX2 quantum dots prepared in Preparation Example 2 were dissolved in n-butylamine to prepare a PbS-PbX2 quantum dot solution with a concentration of 150 mg / mL. The PbS-PbX2 quantum dot solution was spin-coated onto the zinc oxide electron transport layer (spin-coating speed 1800 rpm, spin-coating time 10 s) to obtain a PbS-PbX2 quantum dot layer (thickness 350 nm). YbBr3 was added to N,N-dimethylformamide at a concentration of 10 mg / mL, and after heating and shaking at 50 °C for 20 min, a YbBr3 solution was obtained. 75 μL of YbBr3 solution was spin-coated per square centimeter of PbS-PbX2 quantum dot layer onto the PbS-PbX2 quantum dot layer (spin-coating speed 5000 rpm, spin-coating time 30 s). Then, the layer was annealed at 78 °C for 10 min under nitrogen atmosphere to obtain the modified PbS-PbX2 quantum dot layer.
[0050] S3: Dissolve the PbS-OA quantum dots from Preparation Example 1 in n-hexane to prepare a PbS-OA quantum dot solution with a concentration of 38 mg / mL; spin-coat a layer of PbS-OA quantum dot solution onto the modified PbS-PbX2 quantum dot layer (spin-coating speed 2500 rpm, spin-coating time 10 s) to obtain a PbS-OA quantum dot layer; spread a 0.02 wt% EDT acetonitrile solution on the PbS-OA quantum dot layer, react for 30 s, and then wash with a mixed solution of ethyl acetate and acetonitrile with a volume ratio of 1:2 to obtain a PbS-EDT hole transport layer (thickness 40 nm).
[0051] S5: An Au top electrode (80 nm thick, deposited in two stages: a slow evaporation of 25 nm in the first stage and a rapid evaporation of 55 nm in the second stage) is prepared on the hole transport layer of PbS-EDT by vacuum evaporation to obtain a photovoltaic device.
[0052] Comparative Example 1 It is basically the same as Example 1, except that the YbBr3 solution is not spin-coated.
[0053] The specific preparation method is as follows: S1: Same as step S1 in Example 1.
[0054] S2: The PbS-PbX2 quantum dots prepared in Preparation Example 2 were dissolved in n-butylamine to prepare a PbS-PbX2 quantum dot solution with a concentration of 150 mg / mL. The PbS-PbX2 quantum dot solution was spin-coated onto the zinc oxide electron transport layer (spin-coating speed 1800 rpm, spin-coating time 10 s), and then annealed at 78 °C for 10 min under a nitrogen atmosphere to obtain a PbS-PbX2 quantum dot layer (thickness 350 nm).
[0055] S3: Same as step S3 in Example 1.
[0056] S4: Same as step S4 in Example 1.
[0057] Comparative Example 2 The results are basically the same as in Example 1, except that YbBr3 is directly added to the PbS-PbX2 quantum dot solution.
[0058] The specific preparation method is as follows: S1: Same as step S1 in Example 1.
[0059] S2: The PbS-PbX2 quantum dots prepared in Preparation Example 2 were dissolved in n-butylamine to prepare a PbS-PbX2 quantum dot solution with a concentration of 150 mg / mL. Then, YbBr3 was added to the PbS-PbX2 quantum dot solution at a concentration of 10 mg / L. After heating and shaking at 50 °C for 20 min, a doped PbS-PbX2 quantum dot solution was obtained. The doped PbS-PbX2 quantum dot solution was spin-coated onto the zinc oxide electron transport layer (spin-coating speed 1800 rpm, spin-coating time 10 s), and then annealed at 78 °C for 10 min under a nitrogen atmosphere to obtain a modified PbS-PbX2 quantum dot layer (thickness 350 nm).
[0060] S3: Same as step S3 in Example 1.
[0061] S4: Same as step S4 in Example 1.
[0062] Comparative Example 3 The process is basically the same as in Example 1, except that in step S3, YbCl3 is used instead of YbBr3.
[0063] Example 2 The process is basically the same as in Example 1, except that in step S3, 70 μL of YbBr3 solution is spin-coated per square centimeter of PbS-PbX2 quantum dot layer.
[0064] Example 3 The process is basically the same as in Example 1, except that in step S3, 80 μL of YbBr3 solution is spin-coated per square centimeter of PbS-PbX2 quantum dot layer.
[0065] Example 4 S1: After cleaning the ITO / glass substrate, a cleaned ITO / glass substrate is obtained; zinc oxide nanoparticles are dispersed in a mixed solvent of chloroform and methanol with a volume ratio of 0.5:1.5 to prepare a zinc oxide solution with a concentration of 40 mg / L; the zinc oxide solution is spin-coated onto the ITO glass substrate at a speed of 4000 rpm for 12 s, and the spin-coating is repeated twice to obtain a zinc oxide electron transport layer with a thickness of 130 nm.
[0066] S2: The PbS-PbX2 quantum dots prepared in Preparation Example 2 were dissolved in n-butylamine to prepare a PbS-PbX2 quantum dot solution with a concentration of 120 mg / mL. The PbS-PbX2 quantum dot solution was spin-coated onto the zinc oxide electron transport layer (spin-coating speed 2000 rpm, spin-coating time 8 s) to obtain a PbS-PbX2 quantum dot layer (thickness 300 nm). YbBr3 was added to N,N-dimethylformamide at a concentration of 8 mg / mL, and after heating and shaking at 50 °C for 20 min, a YbBr3 solution was obtained. 78 μL of YbBr3 solution was spin-coated per square centimeter onto the PbS-PbX2 quantum dot layer (spin-coating speed 6000 pm, spin-coating time 20 s). The modified PbS-PbX2 quantum dot layer was then annealed at 75 °C for 12 min under nitrogen atmosphere to obtain the modified PbS-PbX2 quantum dot layer.
[0067] S3: Dissolve the PbS-OA quantum dots from Preparation Example 1 in n-hexane to prepare a PbS-OA quantum dot solution with a concentration of 35 mg / mL; spin-coat a layer of PbS-OA quantum dot solution onto the modified PbS-PbX2 quantum dot layer (spin-coating speed 2000 rpm, spin-coating time 12 s) to obtain a PbS-OA quantum dot layer; spread a 0.01 wt% EDT acetonitrile solution on the PbS-OA quantum dot layer, react for 40 s, and then wash with a mixed solution of ethyl acetate and acetonitrile with a volume ratio of 1:2 to obtain a PbS-EDT hole transport layer (thickness 35 nm).
[0068] S5: An Au top electrode (60 nm thick, deposited in two stages: a slow evaporation of 20 nm in the first stage and a rapid evaporation of 40 nm in the second stage) is prepared on the hole transport layer of PbS-EDT to obtain a photovoltaic device.
[0069] Example 5 S1: After cleaning the ITO glass substrate, a cleaned ITO / glass substrate is obtained; tin oxide nanoparticles are dispersed in a mixed solvent of chloroform and methanol with a volume ratio of 1.5:0.5 to prepare a tin oxide solution with a concentration of 50 mg / L; the tin oxide solution is spin-coated onto the ITO / glass substrate at a speed of 6000 rpm for 8 s, and the spin-coating is repeated twice to obtain a tin oxide electron transport layer with a thickness of 160 nm.
[0070] S2: The PbS-PbX2 quantum dots prepared in Preparation Example 2 were dissolved in n-butylamine to prepare a PbS-PbX2 quantum dot solution with a concentration of 180 mg / mL. The PbS-PbX2 quantum dot solution was spin-coated onto the tin oxide electron transport layer (spin-coating speed 1500 rpm, spin-coating time 12 s) to obtain a PbS-PbX2 quantum dot layer (thickness 400 nm). YbBr3 was added to N,N-dimethylformamide at a concentration of 15 mg / mL, and after heating and shaking at 50 °C for 20 min, a YbBr3 solution was obtained. 73 μL of YbBr3 solution was spin-coated per square centimeter of PbS-PbX2 quantum dot layer onto the PbS-PbX2 quantum dot layer (spin-coating speed 6000 pm, spin-coating time 20 s). Then, the layer was annealed at 80 °C for 8 min under nitrogen atmosphere to obtain the modified PbS-PbX2 quantum dot layer.
[0071] S3: Dissolve the PbS-OA quantum dots from Preparation Example 1 in n-hexane to prepare a PbS-OA quantum dot solution with a concentration of 40 mg / mL; spin-coat a layer of PbS-OA quantum dot solution onto the modified PbS-PbX2 quantum dot layer (spin-coating speed 3000 rpm, spin-coating time 8 s) to obtain a PbS-OA quantum dot layer; spread a 0.03 wt% EDT acetonitrile solution on the PbS-OA quantum dot layer, react for 20 s, and then wash with a mixed solution of ethyl acetate and acetonitrile with a volume ratio of 1:2 to obtain a PbS-EDT hole transport layer (thickness 55 nm).
[0072] S5: An Au top electrode (100 nm thick, deposited in two stages: a slow evaporation of 30 nm in the first stage and a rapid evaporation of 70 nm in the second stage) is prepared on the hole transport layer of PbS-EDT by vacuum evaporation to obtain a photovoltaic device.
[0073] The power conversion efficiency (PCE) of the photovoltaic devices in Examples 1-5 and Comparative Examples 1-3 was tested. PCE is an important parameter for evaluating the performance of photovoltaic cells and is the most direct indicator of the performance of photovoltaic devices. Its calculation formula is as follows: The open-circuit voltage (Voc), short-circuit current (Jsc), and fill factor (FF) are given. Pinc represents the incident light power, which is 100 mW / cm². The test results are shown in Table 1.
[0074] Table 1 As can be seen from the data in Table 1, the photovoltaic device prepared in Example 1 has a high PCE. In Comparative Example 1, no YbBr3 modification was performed, resulting in a lower PCE for the prepared photovoltaic device. In Comparative Example 2, a blending method was used to dope the PbS-PbX2 quantum dot layer, leading to an improved PCE for the prepared photovoltaic device compared to Comparative Example 1, but still significantly lower than that of Example 1. This may be because the blending doping method affected the PbS-PbX2 quantum dots, resulting in a less significant performance improvement. In Comparative Example 3, YbCl3 modification was used, resulting in an improved PCE for the prepared photovoltaic device compared to Comparative Example 1, but still lower than that of Example 1. This may be because bromide ions better passivate defects in the quantum dot layer. In Examples 2 and 3, the amount of YbBr3 modification was adjusted, resulting in some fluctuation in the PCE of the prepared photovoltaic devices compared to Example 1, but still relatively higher PCE. In Examples 4 and 5, the fabrication process parameters were adjusted, resulting in some fluctuation in the PCE of the prepared photovoltaic devices compared to Example 1, but still relatively higher PCE.
[0075] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.
Claims
1. A photovoltaic device, characterized in that, From bottom to top, it includes: a substrate, an electron transport layer, a YbBr3 spin-coated PbS-PbX2 quantum dot layer, a PbS-EDT layer, and a metal layer, where X is Br and / or Cl.
2. The photovoltaic device according to claim 1, characterized in that, The substrate is an ITO glass substrate; And / or: The electron transport layer material is one of zinc oxide and tin oxide, and the thickness of the electron transport layer is 130~160nm.
3. The photovoltaic device according to claim 1, characterized in that, The thickness of the YbBr3-modified PbS-PbX2 quantum dot layer is 300~400 nm. And / or: the thickness of the PbS-EDT layer is 35~55nm; And / or: the thickness of the metal layer is one or more of Au, Ag and Al; the thickness of the metal layer is 60~100nm.
4. The method for fabricating a photovoltaic device according to any one of claims 1 to 3, characterized in that, Includes the following steps: S1: A solution of electron transport layer material is spin-coated onto a substrate to obtain an electron transport layer; S2: Spin-coat a PbS-PbX2 quantum dot solution onto the electron transport layer to obtain a PbS-PbX2 quantum dot layer; spin-coat a YbBr3 solution onto the PbS-PbX2 quantum dot layer, and anneal under an inert atmosphere to obtain a YbBr3-modified PbS-PbX2 quantum dot layer. S3: Spin-coat PbS-OA quantum dot solution onto PbS-PbX2 quantum dot layer to obtain PbS-OA layer; then cover PbS-OA layer with EDT solution for ligand exchange, and after washing, obtain PbS-EDT layer. S4: A metal layer is deposited on the PbS-EDT layer to obtain a photovoltaic device.
5. The method for fabricating a photovoltaic device according to claim 4, characterized in that, In step S1, the concentration of the electron transport layer material solution is 40~60 mg / L, the solvent is a mixed solvent composed of chloroform and methanol, and the volume ratio of chloroform to methanol is (0.5~1.5):(0.5~1.5); the spin coating speed is 4000~6000 rpm, and the spin coating time is 8~12 s.
6. The method for fabricating a photovoltaic device according to claim 4, characterized in that, In step S2, the concentration of the PbS-PbX2 quantum dot solution is 120~180 mg / mL, and the solvent is n-butylamine; And / or: the spin-coating speed of the PbS-PbX2 quantum dot solution is 1500~2000 rpm, and the spin-coating time of the PbS-PbX2 quantum dot solution is 8~12 s.
7. The method for fabricating a photovoltaic device according to claim 4 or 6, characterized in that, In step S2, the concentration of the YbBr3 solution is 8~15 mg / mL, and the solvent is N,N-dimethylformamide; And / or: the spin-coating speed of the YbBr3 solution is 4000~6000 rpm, the spin-coating time of the YbBr3 solution is 8~12s, and 70~80μL of YbBr3 solution is spin-coated per square centimeter of PbS-PbX2 quantum dot layer during the spin-coating process. And / or: The annealing temperature is 75~80℃, and the annealing time is 8~12min.
8. The method for fabricating a photovoltaic device according to claim 4, characterized in that, In step S3, the concentration of the PbS-OA quantum dot solution is 35~40 mg / mL, and the solvent is n-hexane; the solvent of the EDT solution is acetonitrile, and the concentration of the EDT solution is 0.01~0.03 wt%.
9. The method for fabricating a photovoltaic device according to claim 4 or 8, characterized in that, In step S3, the inert atmosphere is a nitrogen atmosphere or an argon atmosphere. And / or: the spin coating speed is 2000~3000 rpm, the spin coating time is 8~12s; the ligand exchange time is 20~40s.
10. The method for fabricating a photovoltaic device according to claim 4, characterized in that, In step S4, the vapor deposition is performed using vacuum vapor deposition.