CsPbBr3 quantum dot modified inverted inorganic perovskite solar cell and preparation method thereof

Abstract

The invention discloses a CsPbBr3 quantum dot modified inverted inorganic perovskite solar cell and a preparation method thereof. Belongs to the technical field of perovskite solar cells, and through CsPbBr3 quantum dot interface modification, the method can effectively inhibit non-radiative recombination, promote efficient extraction and transmission of electrons, reduce charge loss, passivate perovskite thin film surface defects, improve crystallization quality, inhibit crystal boundary defects and optimize the overall performance of the thin film. The modification layer induces a perovskite conduction band / valence band to move downwards at the same time, energy level matching with a PCBM electron transport layer is optimized, electron injection barriers and interface recombination are reduced, and the charge transport efficiency is improved. In addition, the modification layer enhances the built-in electric field and improves the open-circuit voltage. Through the synergistic effect of defect passivation, energy level optimization and built-in electric field enhancement, the photoelectric conversion efficiency (PCE) of the device is improved from 19.61% to 21.47%, and performance breakthrough is achieved.

Description

Technical Field

[0001] This invention belongs to the field of perovskite materials and devices technology, and relates to an inverted inorganic perovskite solar cell modified with CsPbBr3 quantum dots and its preparation method. Background Technology

[0002] With the continued growth of global energy demand and the escalating energy crisis, the overuse of fossil fuels has led to prominent resource shortages and triggered a series of severe environmental problems, including climate change, air pollution, and ecological damage. Frequent extreme weather events, rising sea levels, increased respiratory diseases, and loss of biodiversity are driving a global shift in energy structure and promoting the research and application of renewable energy. Among clean energy sources such as solar, wind, and hydropower, solar energy, with its abundant resources, wide distribution, and high conversion efficiency, demonstrates enormous development potential and has become an important means of addressing the energy crisis.

[0003] In recent years, inverted inorganic perovskite solar cells (PSCs) have gradually become a research hotspot due to their excellent thermal stability, potential low cost, and promising applications in tandem solar cells. Compared with traditional organic-inorganic hybrid perovskite materials, all-inorganic perovskite materials exhibit superior stability under high temperature and high light conditions, making them more suitable for practical applications. However, the development of inverted inorganic PSCs still faces many challenges.

[0004] On the one hand, poor energy level matching between functional layers severely affects carrier separation and transport efficiency; on the other hand, high-density defect states exist at the interface between the perovskite film and the charge transport layer, leading to severe nonradiative recombination losses, which in turn cause device open-circuit voltage ( V OC () significantly reduced. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide an inverted inorganic perovskite solar cell modified with CsPbBr3 quantum dots and its preparation method; in order to solve the key technical problems commonly existing in the field of inverted inorganic perovskite solar cells, such as energy level matching imbalance, excessively high interface defect density and significant open-circuit voltage loss.

[0006] To achieve the above objectives, the present invention employs the following technical solution: A method for preparing an inverted inorganic perovskite solar cell modified with CsPbBr3 quantum dots includes the following steps: Step 1: Pre-treat the conductive glass; Step 2: Spin-coat an aqueous nickel oxide solution onto a conductive glass, anneal it, and then spin-coat a mixed SAM solution onto its surface. After annealing, a hole transport layer is obtained. The mixed SAM solution is a mixed solution of [2-(9H-carbazole-9-yl)ethyl]phosphonic acid and [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid in ethanol. Step 3: Spin-coat a CsPbI3 perovskite precursor solution onto the hole transport layer, and obtain a CsPbI3 perovskite light-absorbing layer after annealing. Step 4: Spin-coat a quantum dot solution onto a CsPbI3 perovskite light-absorbing layer, followed by annealing. The CsPbBr3 quantum dots coated with mesoporous silica nanoparticles are distributed on the CsPbI3 perovskite light-absorbing layer. The grain boundaries and defect-rich areas of the CsPbI3 perovskite light-absorbing layer are enriched with CsPbBr3 quantum dots coated with mesoporous silica nanoparticles. The quantum dot solution is a dispersion of CsPbBr3 quantum dots coated with mesoporous silica nanoparticles in chlorobenzene. The size of the CsPbBr3 quantum dots coated with mesoporous silica nanoparticles is 4 nm-12 nm. Step 5: Prepare a PCBM electron transport layer on the CsPbI3 perovskite light-absorbing layer; Step 6: Fabricate a BCP blocking layer on the PCBM electron transport layer; Step 7: Fabricate a metal electrode on the BCP barrier layer to obtain an inverted perovskite solar cell.

[0007] A further improvement of the present invention is that: Preferably, in step 4, the size of the CsPbBr3 quantum dots coated with mesoporous silica nanoparticles is 8 nm.

[0008] Preferably, in step 2, the concentrations of both [2-(9H-carbazole-9-yl)ethyl]phosphonic acid and [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid in the mixed SAM solution are 1 mg / mL; and the concentration of the nickel oxide aqueous solution is 20 mg / mL.

[0009] Preferably, in step 3, the solute of the CsPbI3 perovskite precursor solution is cesium iodide and lead iodide trioxide, and the solvent is a mixed solution of DMF and DMSO; the concentration is 0.75M.

[0010] Preferably, in step 3, the spin coating of the titanium ore precursor solution is divided into two stages: in stage 1, the rotation speed is 1000 rpm and the time is 10 s; in stage 2, the rotation speed is 4000 rpm and the time is 30 s; the annealing temperature after spin coating is 160°C. o C, annealing time is 50 min.

[0011] Preferably, in step 4, the concentration of the quantum dot solution is 0.025-0.1 mg / mL.

[0012] Preferably, in step 4, the spin coating speed of the quantum dot solution is 4000-6000 rpm, the spin coating time is 30 s, the annealing temperature is 50-100℃, and the annealing time is 3-10 min.

[0013] Preferably, in step 5, the preparation process of the PCBM electron transport layer is as follows: dissolving PCBM in chlorobenzene to obtain a PCBM solution, and spin-coating the PCBM solution onto the CsPbBr3 quantum dot modification layer at a rotation speed of 2000 rpm to obtain the PCBM electron transport layer.

[0014] Preferably, in step 6, the preparation process of the BCP barrier layer is as follows: dissolving BCP powder in isopropanol to obtain a BCP solution, and spin-coating the BCP solution onto the PCBM electron transport layer at a rotation speed of 5000 rpm to obtain the BCP barrier layer.

[0015] An inverted inorganic perovskite solar cell modified with CsPbBr3 quantum dots, prepared by any of the above methods, comprises conductive glass and NiO stacked sequentially from bottom to top. x The structure consists of a SAM hole transport layer, a CsPbI3 perovskite light-absorbing layer, a CsPbBr3 quantum dot modification layer, a PCBM electron transport layer, a BCP blocking layer, and a metal electrode.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention discloses an inverted inorganic perovskite solar cell modified with CsPbBr3 quantum dots and its preparation method. The method involves precisely modifying the perovskite light-absorbing layer by coating CsPbBr3 quantum dots of different sizes with mesoporous silica nanoparticles. Silica possesses excellent light transmittance and optical inertness, thus not affecting the photophysical properties of the quantum dots themselves. Furthermore, the abundant pores of mesoporous silica do not hinder mass transport processes. The introduction of CsPbBr3 quantum dots coated with mesoporous silica nanoparticles enhances the stability of the quantum dots on the perovskite film surface. If the ABX3 lattice of CsPbBr3 quantum dots is simply held together by weak ionic bonds / van der Waals forces, the imbalance in ionic radius matching leads to lattice distortion, amplifying surface defects and ion migration at the nanoscale. Simultaneously, this structure is susceptible to stimulation by water, oxygen, and light, inducing cation desorption, halogen loss, and lattice collapse, resulting in structural instability. The introduction of mesoporous silica nanoparticles significantly improves the stability of the CsPbBr3 quantum dots. Within the pores of mesoporous silica, CsPbBr3 quantum dots can, to a certain extent, block the contact between water, oxygen, and the quantum dots, inhibiting halogen loss, organic cation desorption, and lattice collapse. The rigid silica framework restricts lattice distortion of CsPbBr3 quantum dots, improving the material's heat resistance and mechanical strength, meeting the requirements of component processing and long-term service. Simultaneously, the ordered pore structure of mesoporous silica physically binds the CsPbBr3 quantum dots, restricting their free movement and collisions within the pores, preventing aggregation caused by van der Waals forces or hydrophobic interactions (especially during drying or thin film preparation). Furthermore, the ordered pore structure allows CsPbBr3 quantum dots to be uniformly loaded into each pore, avoiding "pore aggregation" caused by excessively high local concentrations. Compared to amorphous carriers, ordered pores offer greater controllability in loading, enabling "monodispersed" loading of CsPbBr3 quantum dots.

[0017] Experimental studies show that this quantum dot modification strategy can significantly passivate defect states on the surface of perovskite films, optimize crystal quality, and effectively suppress the formation of grain boundary defects, thereby achieving a comprehensive improvement in the overall quality of the film. Regarding carrier transport, this modification layer can significantly suppress nonradiative recombination processes in perovskite, promote efficient extraction and directional transport of interface electrons, and reduce charge transport losses. In terms of energy level modulation, CsPbBr3 quantum dot modification shifts the conduction and valence bands of the perovskite film downwards, optimizing the energy level alignment between it and the PCBM electron transport layer, reducing electron transfer barriers and interface recombination, and further enhancing charge transport and extraction efficiency, laying an important foundation for improving device performance. Simultaneously, the enhancement of the built-in electric field improves the device's... V OCBased on the synergistic effect of defect passivation, energy level optimization and built-in electric field enhancement, this invention significantly improves the performance of inverted inorganic perovskite solar cells using CsPbBr3 quantum dots as the interface modification layer, increasing the photoelectric conversion efficiency (PCE) from 19.61% to 21.47%.

[0018] Furthermore, based on size, CsPbBr3 quantum dots coated with mesoporous silica nanoparticles can be classified into S-order, M-order, and L-order, with S-order having a size of 4 nm, M-order having a size of 8 nm, and L-order having a size of 12 nm. M-sized CsPbBr3 quantum dots, due to their size being closest to the Bohr radius of CsPbBr3 (7 nm), exhibit the strongest quantum confinement effect. S-sized quantum dots are relatively too small, resulting in a sharp increase in the surface defect state density, leading to insufficient passivation and a weaker quantum confinement effect. L-sized quantum dots are much larger than the Bohr radius, thus exhibiting a very weak quantum confinement effect. Moreover, when applied to the surface of perovskite thin films, M-sized quantum dots can form a "critical coupling" with the film, effectively suppressing nonradiative coincidence. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the CsPbI3 perovskite solar cell described in Embodiment 1 of the present invention; Wherein: 1 is the ITO layer, 2 is the hole transport layer, 3 is the perovskite light-absorbing layer, 4 is the electron transport layer, 5 is the blocking layer, and 6 is the metal electrode. Figure 2 This is a schematic diagram of CsPbBr3 quantum dots coated with mesoporous silica nanoparticles introduced in this invention. Figure 3 This is a comparison of XRD patterns of the unmodified and modified CsPbBr3 quantum dot perovskite light-absorbing layers described in Example 1 of this invention. Figure 4 For the present invention Figure 2 These are SEM comparison images of the unmodified and modified CsPbBr3 quantum dot perovskite light-absorbing layers described in Example 1 of this invention. Figure 5 The PL spectra of the perovskite light-absorbing layer with and without CsPbBr3 quantum dots modified on the surface of the perovskite light-absorbing layer as described in Example 1 of the present invention; Figure 6 The TRPL spectra of the perovskite light-absorbing layer in Example 1 of this invention are those of the unmodified and CsPbBr3 quantum dot-modified perovskite light-absorbing layers. Figure 7 This is a comparison image of the UPS of the unmodified and modified CsPbBr3 quantum dot perovskite light-absorbing layers described in Example 1 of this invention; Figure 8This refers to the perovskite solar cells described in Example 1 of the present invention, specifically the perovskite solar cells with and without CsPbBr3 quantum dot modification on the surface of the perovskite light-absorbing layer. CV curve; Figure 9 The current density-voltage ratio of perovskite solar cells with and without CsPbBr3 quantum dots modified on the surface of the perovskite light-absorbing layer as described in Example 1 of this invention is shown in Example 1. JV )curve; Figure 10 The stability of perovskite solar cells after unmodified and modified CsPbBr3 quantum dots as described in Example 1 of this invention; Figure 11 Examples 1-9 show the current density-voltage ratio of perovskite solar cells after modification of the perovskite light-absorbing layer with CsPbBr3 quantum dots of different concentrations and sizes. JV (Curve graph) Detailed Implementation

[0020] The present invention will now be described in further detail with reference to the accompanying drawings: To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0021] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0022] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0023] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0024] This invention discloses a method for preparing an inverted inorganic perovskite solar cell modified with CsPbBr3 quantum dots, comprising the following steps: Step 1: Clean the ITO conductive glass; Use a special blade to cut the ITO glass into small pieces of 2.5 × 2.5 cm. After cleaning with acetone, isopropanol, and ethanol, dry them with an air compressor before use.

[0025] Step 2, prepare the hole transport layer; The hole transport layer solution was prepared as follows: 20 mg of nickel oxide was dissolved in 1 mL of ultrapure water and stirred at room temperature for 5 min. The solution was then transferred to an ultrasonic machine and sonicated for 5 min. After filtration using a 0.22 μm aqueous filter, a nickel oxide aqueous solution with a concentration of 20 mg / mL was obtained. 1 mg of [2-(9H-carbazole-9-yl)ethyl]phosphonic acid and 1 mg of [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid were dissolved separately in 1 mL of ethanol and stirred at room temperature for 2-3 h to obtain two SAM solutions with a concentration of 1 mg / mL. The two SAM solutions were then mixed in a 1:1 ratio for later use.

[0026] The ITO conductive glass from step 1 was treated with ultraviolet ozone for 15 min, and a nickel oxide layer was prepared by solution spin coating at a speed of 4000 rpm for 30 s. The spin-coated substrate was then placed in a 100°C container. o Annealing was performed on a hot plate at C for 30 min, followed immediately by spin coating of a mixed SAM solution in a nitrogen-filled oven at 4000 rpm for 30 s. The spin-coated substrate was then placed in a 100°C environment. o The NiO was annealed on a hot plate for 10 minutes to obtain NiO. x / SAM hole transport layer; Step 3: Prepare a CsPbI3 perovskite light-absorbing layer; The preparation method of CsPbI3 perovskite precursor solution is as follows: Cesium iodide (CsI) and lead hydrogen iodide tris (HPbI3) are dissolved in a mixed solvent of DMF and DMSO (V / V = 4:1) according to the stoichiometric ratio to prepare a CsPbI3 perovskite precursor solution with a concentration of 0.75 M. The perovskite precursor solution is stirred for 6-8 h, and then filtered through a 0.45 μm polytetrafluoroethylene filter before use.

[0027] Before spin-coating the perovskite precursor solution, the substrate obtained in step 2 is left untreated. The prepared perovskite precursor solution is then spin-coated onto the ITO / NiO substrate. xThe spin coating process on the SAM substrate surface is divided into two stages: Step 1, with a spin speed of 1000 rpm and a time of 10 s; Step 2, with a spin speed of 4000 rpm and a time of 30 s. Subsequently, ITO / NiO... x The SAM / CsPbI3 substrate was annealed on a hot plate at a temperature of 160°C. o C, annealing time is 50 min. After annealing, a perovskite light-absorbing layer is obtained, and the thickness of the prepared perovskite light-absorbing layer is 400-450 nm.

[0028] Step 4: Prepare a CsPbBr3 quantum dot modification layer. CsPbBr3 quantum dot powder coated with mesoporous silica nanoparticles (approximately 100 nm in size) of different sizes (4 nm, 8 nm, 12 nm) is dispersed in chlorobenzene at a concentration of 0.025-0.1 mg / mL. The aforementioned silica mesoporous material coating of CsPbBr3 quantum dots allows the CsPbBr3 quantum dots to grow within the pores of the mesoporous silica material. Each mesoporous silica nanoparticle (MSN) contains multiple channels, and each channel also contains multiple quantum dots. The pores of the mesoporous silica act as a microreactor of a defined size, providing confined space for the nucleation and growth of quantum dots, thus determining the size of the grown quantum dots and consequently their properties.

[0029] The prepared quantum dot solution was spin-coated onto ITO / NiO. x On a / SAM / CsPbI3 surface, a spin-coating process was performed at a speed of 5000 rpm for 30 s, followed by annealing at a temperature of 50-100℃ for 3-10 min to obtain a CsPbBr3 quantum dot modified layer (CsPbBr3QDs). CsPbBr3 quantum dots primarily enhance perovskite properties through a synergistic mechanism of "defect passivation" and "interface enhancement." Firstly, there is efficient defect passivation: quantum dots preferentially accumulate on defect-dense surfaces and grain boundaries, and the Br2 on their surface... - Ions can strongly anchor uncoordinated Pb² in perovskites + The quantum dots effectively eliminate defect states that lead to non-radiative recombination, directly resulting in improved open-circuit voltage and fill factor. Secondly, optimized carrier management is achieved: quantum dots form beneficial energy level arrangements at the interface, acting as "ladders" for charge extraction or "selective barriers" for transport, promoting the separation and collection of photogenerated carriers, thereby increasing current density. Furthermore, it enhances stability: quantum dots enriched at grain boundaries act like "nanopoles," blocking the intrusion channels of environmental moisture and oxygen while strengthening grain boundaries, significantly improving the long-term stability of the film. In short, the quantum dot-modified layer is an active, multifunctional layer that achieves a triple synergistic effect of defect repair, optimized charge transport, and enhanced stability through precise positioning.

[0030] Step 5: Prepare the electron transport layer; The electron transport layer solution was prepared as follows: 20 mg of PCBM powder was dissolved in 1 mL of chlorobenzene and stirred for 6-8 h to obtain a PCBM solution. The stirred PCBM solution was filtered and set aside. The electron transport layer was prepared by spin coating. The PCBM solution was spin-coated onto the interface modification layer prepared in step 4 at a speed of 2000 rpm for 30 s to form the electron transport layer, resulting in ITO / NiO. x / SAM / CsPbI3 / CsPbBr3QDs / PCBM.

[0031] Step 6: Prepare the barrier layer; The barrier layer solution was prepared as follows: 0.5 mg of BCP powder was dissolved in 1 mL of isopropanol and stirred at 100 °C for 0.5–1 h to obtain a BCP solution. The stirred BCP solution was then filtered and set aside. The BCP solution was spin-coated onto the electron transport layer prepared in step 5 at 5000 rpm for 30 s to obtain ITO / NiO. x / SAM / CsPbI3 / CsPbBr3QDs / PCBM / BCP.

[0032] Step 7: Prepare the metal electrode; In step 6, the surface of the barrier layer prepared was coated with Ag with a thickness of approximately 80 nm using a vacuum evaporation device to obtain an ITO / NiO structure. x Perovskite solar cell devices using SAM / CsPbI3 / CsPbBr3QDs / PCBM / BCP / Ag.

[0033] An inverted inorganic perovskite solar cell fabricated by the above-described method comprises, from bottom to top, an ITO conductive glass, a hole transport layer, a CsPbI3 perovskite light-absorbing layer, a CsPbBr3 quantum dot modification layer, a PCBM electron transport layer, a BCP blocking layer, and a metal electrode. The grain boundaries and defect-rich areas of the perovskite light-absorbing layer are enriched with CsPbBr3 quantum dots coated with mesoporous silica nanoparticles. This means that the CsPbBr3 quantum dot modification layer on the perovskite light-absorbing layer is not a dense, continuous capping layer, but rather selectively and non-uniformly distributed on the surface of the perovskite light-absorbing layer. In particular, CsPbBr3 quantum dots preferentially aggregate and fill the grain boundaries of the perovskite polycrystalline thin film. The grain boundaries of the perovskite thin film contain a large number of uncoordinated ions and defects, providing preferred nucleation and anchoring sites for the CsPbBr3 quantum dot precursors.

[0034] The following description, in conjunction with specific embodiments, provides further details.

[0035] Comparative Example 1 Step 1: Clean the ITO conductive glass. Use a special blade to cut the ITO glass into small pieces of 2.5 × 2.5 cm. Clean the pieces with acetone, isopropanol, and ethanol, then dry them with an air compressor until ready for use.

[0036] Step 2, Preparation of the hole transport layer. The hole transport layer solution is prepared as follows: 20 mg of nickel oxide is dissolved in 1 mL of ultrapure water and stirred at room temperature for 5 min. The solution is then transferred to an ultrasonic machine and sonicated for 5 min. After filtration through a 0.22 μm aqueous filter, an aqueous nickel oxide solution is obtained for later use. 1 mg of [2-(9H-carbazole-9-yl)ethyl]phosphonic acid and 1 mg of [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid are dissolved in 1 mL of ethanol and stirred at room temperature for 2-3 h, respectively, to obtain two SAM solutions with a concentration of 1 mg / mL. The two SAM solutions are then mixed in a 1:1 ratio for later use.

[0037] The ITO conductive glass from step 1 was treated with ultraviolet ozone for 15 min, and a nickel oxide layer was prepared by solution spin coating at a speed of 4000 rpm for 30 s. The spin-coated substrate was then placed in a 100°C container. o Annealing was performed on a hot plate at C for 30 min, followed immediately by spin coating of a mixed SAM solution in a nitrogen-filled oven at 4000 rpm for 30 s. The spin-coated substrate was then placed in a 100°C environment. o The NiO was annealed on a hot plate for 10 minutes to obtain NiO. x / SAM hole transport layer; Step 3: Preparation of the CsPbI3 perovskite light-absorbing layer. The CsPbI3 perovskite precursor solution is prepared by dissolving cesium iodide (CsI) and lead hydrogen iodide tris (HPbI3) in a stoichiometric ratio in a mixed solvent of DMF and DMSO (V / V = 4:1) to prepare a 0.75 M CsPbI3 perovskite precursor solution. The perovskite precursor solution is stirred for 6-8 h, and then filtered through a 0.45 μm polytetrafluoroethylene filter before use.

[0038] Before spin-coating the perovskite precursor solution, the substrate obtained in step 2 is left untreated. The prepared perovskite precursor solution is then spin-coated onto ITO / NiO. x The spin coating process on the SAM substrate surface is divided into two stages: Step 1, with a spin speed of 1000 rpm and a time of 10 s; Step 2, with a spin speed of 4000 rpm and a time of 30 s. Subsequently, ITO / NiO... xThe SAM / CsPbI3 substrate was annealed on a hot plate at a temperature of 160°C. o C, annealing time is 50 min. After annealing, a perovskite light-absorbing layer is obtained, and the thickness of the prepared perovskite light-absorbing layer is 400-450 nm.

[0039] Step 4: Preparation of the electron transport layer. The electron transport layer solution is prepared as follows: 20 mg of PCBM powder is dissolved in 1 mL of chlorobenzene and stirred for 6-8 h to obtain a PCBM solution. The stirred PCBM solution is filtered and set aside. The electron transport layer is prepared by spin-coating. The PCBM solution is spin-coated onto the perovskite light-absorbing layer prepared in step 3 at a speed of 2000 rpm for 30 s to form the electron transport layer, resulting in ITO / NiO. x / SAM / CsPbI3 / PCBM.

[0040] Step 5: Prepare the barrier layer. The barrier layer solution is prepared by dissolving 0.5 mg of BCP powder in 1 mL of isopropanol and stirring at 100 °C for 0.5–1 h to obtain a BCP solution. Filter the stirred BCP solution and set it aside. Spin-coat the BCP solution onto the electron transport layer prepared in step 5 at 5000 rpm for 30 s to obtain ITO / NiO. x / SAM / CsPbI3 / PCBM / BCP.

[0041] Step 6: Fabrication of the metal electrode. Using a vacuum evaporation device, an Ag layer with a thickness of approximately 80 nm is deposited on the surface of the barrier layer prepared in Step 6 to serve as the metal electrode, resulting in an ITO / NiO structure. x Perovskite solar cell devices using SAM / CsPbI3 / PCBM / BCP / Ag.

[0042] Example 1 Step 1: Clean the ITO conductive glass. Cut the ITO conductive glass into 2.5 × 2.5 cm pieces using a special cutting tool. Clean with acetone, isopropanol, and ethanol, then dry with an air compressor until ready for use.

[0043] Step 2, Preparation of the hole transport layer. The hole transport layer solution is prepared as follows: 20 mg of nickel oxide is dissolved in 1 mL of ultrapure water and stirred at room temperature for 5 min. The solution is then transferred to an ultrasonic machine and sonicated for 5 min. After filtration through a 0.22 μm aqueous filter, an aqueous nickel oxide solution is obtained for later use. 1 mg of [2-(9H-carbazole-9-yl)ethyl]phosphonic acid and 1 mg of [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid are dissolved in 1 mL of ethanol and stirred at room temperature for 2-3 h, respectively, to obtain two SAM solutions with a concentration of 1 mg / mL. The two SAM solutions are then mixed in a 1:1 ratio for later use. The ITO conductive glass from step 1 was treated with ultraviolet ozone for 15 min, and a nickel oxide layer was prepared by solution spin coating at a speed of 4000 rpm for 30 s. The spin-coated substrate was then placed in a 100°C container. o Annealing was performed on a hot plate at C for 30 min, followed immediately by spin coating of a mixed SAM solution in a nitrogen-filled oven at 4000 rpm for 30 s. The spin-coated substrate was then placed in a 100°C environment. o The NiO was annealed on a hot plate for 10 minutes to obtain NiO. x / SAM hole transport layer; Step 3, Preparation of CsPbI3 perovskite light-absorbing layer. The CsPbI3 perovskite precursor solution is prepared as follows: Cesium iodide (CsI) and lead-iodine trihydride (HPbI3) are dissolved in a mixed solvent of DMF and DMSO (V / V = 4:1) according to a stoichiometric ratio to prepare a 0.75 M CsPbI3 perovskite precursor solution. The perovskite precursor solution is stirred for 6-8 h, and then filtered through a 0.45 μm polytetrafluoroethylene filter before use.

[0044] Before spin-coating the perovskite precursor solution, the substrate obtained in step 2 is left untreated. The prepared perovskite precursor solution is then spin-coated onto ITO / NiO. x The spin coating process on the SAM substrate surface is divided into two stages: Step 1, with a spin speed of 1000 rpm and a time of 10 s; Step 2, with a spin speed of 4000 rpm and a time of 30 s. Subsequently, ITO / NiO... x The SAM / CsPbI3 substrate was annealed on a hot plate at a temperature of 160°C. o C, annealing time is 50 min. After annealing, a perovskite light-absorbing layer is obtained, and the thickness of the prepared perovskite light-absorbing layer is 400-450 nm.

[0045] Step 4: Spin-coating CsPbBr3 quantum dots coated with mesoporous silica nanoparticles; 8 nm CsPbBr3 quantum dot powder coated with mesoporous silica nanoparticles (M-CsPbBr3QDs) is dispersed in chlorobenzene for later use, with a specific concentration of 0.05 mg / mL. Figure 2 As shown.

[0046] The prepared quantum dot solution was spin-coated onto ITO / NiO. x The SAM / CsPbI3 surface was spin-coated at 5000 rpm for 30 s, followed by annealing at 70°C. o C, with an annealing time of 5 min, M-CsPbBr3QDs modification was prepared on the surface of the perovskite light-absorbing layer.

[0047] Step 5: Preparation of the electron transport layer. The electron transport layer solution was prepared by dissolving 20 mg of PCBM powder in 1 mL of chlorobenzene and stirring for 6 h to obtain a PCBM solution. The stirred PCBM solution was filtered and set aside. The electron transport layer was prepared by spin-coating. The PCBM solution was spin-coated onto the interface modification layer prepared in step 4 at 2000 rpm for 30 s to form the electron transport layer, yielding ITO / NiO. x / SAM / CsPbI3 / M-CsPbBr3QDs / PCBM.

[0048] Step 6: Prepare the barrier layer. The barrier layer solution is prepared by dissolving 0.5 mg of BCP powder in 1 mL of isopropanol and stirring at 100 °C for 1 h to obtain a BCP solution. Filter the stirred BCP solution and set it aside. Spin-coat the BCP solution onto the electron transport layer prepared in step 5 at 5000 rpm for 30 s to obtain ITO / NiO. x / SAM / CsPbI3 / M-CsPbBr3QDs / PCBM / BCP.

[0049] Step 7: Fabrication of the metal electrode. Using a vacuum evaporation device, an Ag layer with a thickness of approximately 80 nm is deposited on the surface of the barrier layer prepared in Step 6 to obtain an ITO / NiO structure. x Perovskite solar cell devices using SAM / CsPbI3 / M-CsPbBr3QDs / PCBM / BCP / Ag.

[0050] In this embodiment, an inverted inorganic perovskite solar cell with an M-CsPbBr3QDs concentration of 0.05 mg / mL was prepared.

[0051] like Figure 1As shown, the perovskite solar cell structure prepared by the above method consists of, from bottom to top, a glass substrate, a hole transport layer, a CsPbI3 perovskite light-absorbing layer, a PCBM electron transport layer, a BCP blocking layer, and an Ag electrode. The CsPbBr3QDs modification layer has a concentration of 0.05 mg / mL and a size of 8 nm.

[0052] like Figure 2 The image shows the pores of mesoporous silica nanoparticles coated with CsPbBr3 quantum dot powder. Each mesoporous MSN contains multiple channels, and each channel also contains multiple quantum dots.

[0053] like Figure 3 As shown, the crystallinity of the perovskite film modified with CsPbBr3QDs is enhanced, and the intensity of the crystal plane peaks is significantly enhanced compared with the unmodified film, resulting in better film quality.

[0054] like Figure 4 As shown, the unmodified perovskite film surface exhibits small grain size, obvious pores and gaps at grain boundaries, and numerous surface defects. The perovskite film modified with quantum dots coated with silica mesoporous material shows a slightly larger grain size compared to the Control group, and a significant reduction in pores and gaps at grain boundaries, resulting in improved film density. The red circled area shows that the silica-coated CsPbBr3QDs (light-colored small particles in the figure) are mainly distributed at the grain boundaries of the perovskite grains, achieving targeted modification of the perovskite film grain boundary region and exhibiting significant aggregation.

[0055] like Figure 5 As shown, the PL intensity of the perovskite film is improved after modifying the surface of the perovskite light-absorbing layer with CsPbBr3QDs. This indicates that the modification with CsPbBr3QDs can effectively suppress the non-radiative recombination process in the perovskite film and improve the fill factor.

[0056] like Figure 6 As shown, the average carrier lifetime of the perovskite film after modification with CsPbBr3QDs on the surface of the perovskite light-absorbing layer is higher than that of the unmodified film, further indicating that the CsPbBr3QDs treatment can effectively suppress nonradiative recombination in the film and reduce trap trapping.

[0057] like Figure 7 As shown, the perovskite light-absorbing layer modified with CsPbBr3QDs has lower conduction and valence bands, which makes the optimized perovskite light-absorbing layer and electron transport layer have a more matched energy arrangement, resulting in an increase in the open-circuit voltage of the device.

[0058] like Figure 8As shown, the perovskite solar cells treated with CsPbBr3QDs have a higher built-in potential. The increased built-in electric field between the electron transport layer and the perovskite light-absorbing layer is beneficial for charge separation and collection, thus increasing the open-circuit voltage.

[0059] like Figure 9 As shown, the open-circuit voltage and fill factor of the inverted inorganic perovskite solar cell treated with CsPbBr3QDs are significantly improved, with an open-circuit voltage of 1.28 V and a fill factor of 80.94%, respectively, and a device efficiency of 21.47%.

[0060] Table 1 Performance test results of perovskite solar cells prepared in Example 1 and the comparative example

[0061] like Figure 10 As shown, the stability of the modified device was tested. The optimal device could still maintain 95.39% of its initial efficiency after aging for 900 h, demonstrating excellent stability.

[0062] Example 2 In this embodiment, the concentration of modified M-CsPbBr3QDs is 0.025 mg / mL, and the other parts not involved are the same as in Example 1.

[0063] Example 3 In this embodiment, the concentration of modified M-CsPbBr3QDs is 0.1 mg / mL, and the other parts not involved are the same as in Example 1.

[0064] Example 4 In this embodiment, the size of the modified CsPbBr3QDs is 4 nm (S-CsPbBr3QDs), the concentration is 0.025 mg / mL, and the rest of the parts not involved are the same as in Example 1.

[0065] Example 5 In this embodiment, the size of the modified CsPbBr3QDs is 4 nm (S-CsPbBr3QDs), the concentration is 0.05 mg / mL, and the other parts not involved are the same as in Example 1.

[0066] Example 6 In this embodiment, the size of the modified CsPbBr3QDs is 4 nm (S-CsPbBr3QDs), the concentration is 0.10 mg / mL, and the rest of the parts not involved are the same as in Example 1.

[0067] Example 7 In this embodiment, the size of the modified CsPbBr3QDs is 12 nm (L-CsPbBr3QDs), the concentration is 0.025 mg / mL, and the rest of the parts not involved are the same as in Example 1.

[0068] Example 8 In this embodiment, the size of the modified CsPbBr3QDs is 12 nm (L-CsPbBr3QDs), the concentration is 0.05 mg / mL, and the rest of the parts not involved are the same as in Example 1.

[0069] Example 9 In this embodiment, the size of the modified CsPbBr3QDs is 12 nm (L-CsPbBr3QDs), the concentration is 0.10 mg / mL, and the other parts not involved are the same as in Example 1.

[0070] See Figure 11 For Examples 1-9, the current density-voltage (V / V) ratio of perovskite solar cells after modification of the perovskite light-absorbing layer with CsPbBr3QDs of different concentrations and sizes is used. JV The graph shows that modification with CsPbBr3QDs improved the efficiency of the fabricated devices, with the highest efficiency achieved at a concentration of 0.05 mg / mL and a size of 8 nm (M-CsPbBr3QDs). This size achieves optimal synergy between spatial matching and functional characteristics: the M-type quantum dots are highly matched to the perovskite grain boundary size, enabling effective embedding deep into the grain boundaries and sufficient passivation of surface defects; its energy level structure ensures efficient charge extraction while the coating thickness is within the optimal range for carrier tunneling; and the protective layer formed at the interface provides optimal environmental barrier capability and stress buffering. This triple synergistic effect between defect passivation efficiency, charge transport dynamics, and interface stability is remarkable.

[0071] Example 10 In this embodiment, the modified CsPbBr3QDs solution was spin-coated onto the perovskite film at a speed of 4000 rpm, and the remaining parts were the same as in Example 1.

[0072] Example 11 In this embodiment, the modified CsPbBr3QDs solution was spin-coated onto the perovskite film at a speed of 6000 rpm, and the remaining parts were the same as in Example 1.

[0073] Example 12 In this embodiment, after spin-coating the modified CsPbBr3QDs solution, the substrate was annealed on a 70 °C hot plate for 10 min. The remaining parts were the same as in Example 1.

[0074] Example 13 In this embodiment, after spin-coating the modified CsPbBr3QDs solution, the substrate was annealed on a 70 °C hot plate for 3 min. The remaining parts were the same as in Example 1.

[0075] Example 14 In this embodiment, after spin-coating the modified CsPbBr3QDs solution, the substrate was annealed on a 50 °C hot plate for 5 min. The remaining parts are the same as in Example 1.

[0076] Example 15 In this embodiment, after spin-coating the modified CsPbBr3QDs solution, the substrate was annealed on a hot plate at 100 °C for 5 min. The remaining parts were the same as in Example 1.

[0077] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing an inverted inorganic perovskite solar cell modified with CsPbBr3 quantum dots, characterized in that, Includes the following steps: Step 1: Pre-treat the conductive glass; Step 2: Spin-coat an aqueous nickel oxide solution onto a conductive glass, anneal it, and then spin-coat a mixed SAM solution onto its surface. After annealing, a hole transport layer is obtained. The mixed SAM solution is a mixed solution of [2-(9H-carbazole-9-yl)ethyl]phosphonic acid and [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid in ethanol. Step 3: Spin-coat a CsPbI3 perovskite precursor solution onto the hole transport layer, and obtain a CsPbI3 perovskite light-absorbing layer after annealing. Step 4: Spin-coat a quantum dot solution onto a CsPbI3 perovskite light-absorbing layer, followed by annealing. The CsPbBr3 quantum dots coated with mesoporous silica nanoparticles are distributed on the CsPbI3 perovskite light-absorbing layer. The grain boundaries and defect-rich areas of the CsPbI3 perovskite light-absorbing layer are enriched with CsPbBr3 quantum dots coated with mesoporous silica nanoparticles. The quantum dot solution is a dispersion of CsPbBr3 quantum dots coated with mesoporous silica nanoparticles in chlorobenzene. The size of the CsPbBr3 quantum dots coated with mesoporous silica nanoparticles is 4 nm-12 nm. Step 5: Prepare a PCBM electron transport layer on the CsPbI3 perovskite light-absorbing layer; Step 6: Fabricate a BCP blocking layer on the PCBM electron transport layer; Step 7: Fabricate a metal electrode on the BCP barrier layer to obtain an inverted perovskite solar cell.

2. The method for preparing an inverted inorganic perovskite solar cell modified with CsPbBr3 quantum dots according to claim 1, characterized in that, In step 4, the size of the CsPbBr3 quantum dots coated with mesoporous silica nanoparticles is 8 nm.

3. The method for preparing an inverted inorganic perovskite solar cell modified with CsPbBr3 quantum dots according to claim 1, characterized in that, In step 2, the concentrations of [2-(9H-carbazole-9-yl)ethyl]phosphonic acid and [2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl]phosphonic acid in the mixed SAM solution were both 1 mg / mL; the concentration of the nickel oxide aqueous solution was 20 mg / mL.

4. The method for preparing an inverted inorganic perovskite solar cell modified with CsPbBr3 quantum dots according to claim 1, characterized in that, In step 3, the solute of the CsPbI3 perovskite precursor solution is cesium iodide and lead iodide trihydride, and the solvent is a mixed solution of DMF and DMSO; the concentration is 0.75M.

5. The method for preparing an inverted inorganic perovskite solar cell modified with CsPbBr3 quantum dots according to claim 1, characterized in that, In step 3, the spin coating of the titanium ore precursor solution is divided into two stages: in stage 1, the spin speed is 1000 rpm and the time is 10 s; in stage 2, the spin speed is 4000 rpm and the time is 30 s; the annealing temperature after spin coating is 160°C. o C, annealing time is 50 min.

6. The method for preparing a CsPbBr3 quantum dot-modified inverted inorganic perovskite solar cell according to claim 1, characterized in that, In step 4, the concentration of the quantum dot solution is 0.025-0.1 mg / mL.

7. The method for preparing an inverted inorganic perovskite solar cell modified with CsPbBr3 quantum dots according to claim 1, characterized in that, In step 4, the spin coating speed of the quantum dot solution is 4000-6000 rpm, the spin coating time is 30 s, the annealing temperature is 50-100℃, and the annealing time is 3-10 min.

8. The method for preparing an inverted inorganic perovskite solar cell modified with CsPbBr3 quantum dots according to claim 1, characterized in that, In step 5, the preparation process of the PCBM electron transport layer is as follows: PCBM is dissolved in chlorobenzene to obtain a PCBM solution, and the PCBM solution is spin-coated onto the CsPbBr3 quantum dot modification layer at a rotation speed of 2000 rpm to obtain the PCBM electron transport layer.

9. The method for preparing a CsPbBr3 quantum dot-modified inverted inorganic perovskite solar cell according to claim 1, characterized in that, In step 6, the preparation process of the BCP barrier layer is as follows: dissolve BCP powder in isopropanol to obtain a BCP solution, and spin-coat the BCP solution onto the PCBM electron transport layer at a speed of 5000 rpm to obtain the BCP barrier layer.

10. An inverted inorganic perovskite solar cell modified with CsPbBr3 quantum dots, prepared by any one of claims 1-9, characterized in that, Including conductive glass and NiO stacked from bottom to top x The structure consists of a SAM hole transport layer, a CsPbI3 perovskite light-absorbing layer, a CsPbBr3 quantum dot modification layer, a PCBM electron transport layer, a BCP blocking layer, and a metal electrode.

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