An inorganic perovskite solar cell based on surface halide substitution and a preparation method thereof
By spin-coating a dimethylamine halide solution onto the surface of a perovskite layer and then annealing it, an inorganic perovskite component with compressive strain is formed, which solves the stability problem of CsPbI3 thin films, improves photoelectric efficiency and stability, and is suitable for small-size and large-area modules.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
- Filing Date
- 2024-12-06
- Publication Date
- 2026-07-21
AI Technical Summary
In inorganic perovskite solar cells, the black phase CsPbI3 has poor stability and is easily affected by residual tensile strain, leading to defect formation and non-radiative recombination losses, which affect photoelectric efficiency and stability.
A dimethylamine halide (DMAX, X = Cl or Br) solution is spin-coated onto the surface of the perovskite layer and then annealed. The reaction occurs only on the surface, forming a gradient of inorganic perovskite components CsPbI3-yXy (X = Br or Cl). This introduces compressive strain, passivates surface halide vacancies, and improves film stability.
By replacing the surface with halides, the photoelectric efficiency and thin film stability of inorganic perovskite solar cells were significantly improved, with the photoelectric conversion efficiency increasing to 21.2% and 19.2%, respectively. The efficiency remained stable after long-term operation in air, and the lifespan was extended.
Smart Images
Figure CN119816084B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of solar cell technology, specifically relating to an inorganic perovskite solar cell based on surface halide substitution and its preparation method. Background Technology
[0002] Perovskite solar cells possess excellent photoelectric properties, such as high carrier mobility, long carrier diffusion length, and high defect tolerance, making them one of the most promising new types of solar cells. Laboratory-certified efficiencies based on organic-inorganic hybrid perovskites have reached 26.7%, approaching the power conversion efficiency of commercial silicon. However, due to the presence of volatile organic cations (such as methylamine and formamidinium), organic-inorganic hybrid perovskites exhibit poor chemical and thermal stability. This has led to increasing attention being paid to inorganic perovskite solar cells with higher stability in recent years.
[0003] Among numerous inorganic perovskite materials, CsPbI3 possesses a relatively ideal bandgap of 1.7 eV, making it promising for applications in both single-junction and multi-junction solar cells. However, the highly optically active black-phase CsPbI3 exhibits poor stability at room temperature and readily transforms into the optically inactive delta phase. Therefore, stabilizing black-phase CsPbI3 has become a pressing technical challenge.
[0004] Current research indicates that residual tensile strain is the main factor leading to phase instability in CsPbI3 perovskite films under an inert atmosphere. Typically, the occurrence of residual tensile strain can be attributed to the mismatch in thermal expansion coefficients between the perovskite film and the substrate during high-temperature annealing and crystallization. The presence of residual tensile strain also further promotes defect formation and leads to non-radiative recombination losses. Meanwhile, studies have found that perovskite films with residual compressive strain exhibit superior black-phase stability compared to perovskite films with residual tensile strain or no residual strain. Therefore, inducing residual compressive strain in CsPbI3 perovskite films may be an effective strategy to improve the stability of inorganic perovskite solar cells. Summary of the Invention
[0005] This invention provides an inorganic perovskite solar cell based on surface halide substitution and its preparation method, which constructs a benign compressive strain of CsPbI3 perovskite, thereby improving the photoelectric efficiency and phase stability of the solar cell.
[0006] To achieve the above objectives, the present invention adopts the following technical solution:
[0007] An inorganic perovskite solar cell based on surface halide substitution is disclosed. In the solar cell, the perovskite layer is a modified perovskite layer. A dimethylamine halide (DMAX, X = Cl or Br) solution is spin-coated onto the surface of the perovskite layer and then annealed. During the substitution process, DMAX only reacts with the surface of the perovskite layer and is subsequently removed by annealing, at which point the reaction stops. The composition of the perovskite layer, except for the surface, remains unchanged. The dimethylamine cations are easily removed during the thin film annealing and crystallization process, ensuring the purity of the inorganic thin film components.
[0008] The solvent for the dimethylamine halide (DMAX, X = Cl or Br) solution is isopropanol (IPA), N,N-dimethylformamide (DMF) or dimethyl sulfoxide (DMSO).
[0009] The concentration of the dimethylamine halide (DMAX, X = Cl or Br) solution is 0.5-2 mM;
[0010] The dimethylamine halide (DMAX, X = Cl or Br) solution was spin-coated on the perovskite film surface at a speed of 3000-6000 rpm.
[0011] The annealing temperature is 100-300℃, and the annealing time is 1-10 minutes;
[0012] The perovskite film is an inorganic perovskite film, and the structure of the inorganic perovskite is ABX3, wherein A is mainly Cs, B is one or more of Pb, Sn, and Ge, and X is one or more of I, Br, Cl, and F.
[0013] The core functional layer of the solar cell can be a formal structure or an inverted structure. The formal structure consists of an electron transport layer, a perovskite light-absorbing layer, and a hole transport layer from the substrate upwards. The inverted structure consists of a hole transport layer, a perovskite light-absorbing layer, and an electron transport layer from the substrate upwards.
[0014] Beneficial effects: This invention provides an inorganic perovskite solar cell based on surface halide substitution and its preparation method, which has the following advantages compared with the prior art:
[0015] 1. CsPbI3 thin films are treated with DMAX (X = Cl or Br) and then annealed. Annealing drives the crystallization of CsPbI3 thin films and simultaneously evaporates and removes DMA. + To ensure the purity of the CsPbI3 film composition, DMAX reacts only with the film surface, causing its surface composition to transform into a mixed halide CsPbI3. 3-y X y (X = Br or Cl), when I - smaller Br - or Cl- During substitution, a gradient of inorganic perovskite components CsPbI is formed on the perovskite surface. 3-y X y (X = Br or Cl) reduces the lattice size. This surface halide substitution causes lattice contraction, thereby inducing equivalent compressive strain near the perovskite surface. The compressive strain, which is uniformly distributed along the film, effectively passivates the surface halide vacancies, helps stabilize the phase state of the CsPbI3 perovskite film, and suppresses photoinduced ion migration.
[0016] 2. The replacement of halide components on the perovskite surface provides additional halogen vacancies on the passivated surface by halide anions, resulting in fewer defects in the CsPbI3 film and effectively suppressing non-radiative recombination, which helps to improve the photoelectric efficiency of solar cells.
[0017] 3. The modified solar cell of this invention has a diameter of 0.16 cm. 2 Small size and 23.9 cm 2 The solar cell modules achieved power conversion efficiencies of 21.2% and 19.2%, respectively. After being exposed to air for more than 1,000 hours and operating continuously for more than 3,200 hours under maximum power point tracking and one solar irradiation, the solar cells showed almost no loss in PCE.
[0018] 4. The surface halide substitution used in this invention mainly involves treating CsPbI3 thin films with DMAX (X = Cl or Br) followed by annealing. The method is simple, easy to operate, and economical. The solar cell devices treated with this method not only have significantly improved photoelectric efficiency but also have significantly improved stability. This invention has both important scientific significance and extremely high industrial application value. Attached Figure Description
[0019] Figure 1 This is a schematic diagram of halide substitution on the surface of CsPbI3 perovskite after treatment with DMAX (X = Br or Cl) in an embodiment of the present invention.
[0020] Figure 2 This is a graph showing the relationship between the peak position of the (110) plane of CsPbI3 extracted from the grazing incidence X-ray diffraction pattern and different X-ray incident angles in an embodiment of the present invention.
[0021] Figure 3 The current-voltage (JV) curves are shown for Comparative Example 1 and Examples 1, 2, and 3.
[0022] Figure 4 The efficiency champion device in Example 4 (effective area 23.9 cm²) 2The current-voltage (JV) curves and power curves are plotted with a geometric fill factor of approximately 0.93.
[0023] Figure 5 The graph shows the standardized photoelectric efficiency versus aging time of the packaged devices prepared in Comparative Example 1 and Examples 1, 2, and 3 under maximum power output in air at 40 °C and under constant sunlight for one day. Detailed Implementation
[0024] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments: Example 1
[0025] A method for fabricating an inorganic perovskite solar cell based on surface halide substitution includes the following steps:
[0026] The pre-patterned FTO substrate was sequentially cleaned with deionized water, acetone, and isopropanol for 15 minutes each, dried with nitrogen, and then treated with UV-ozone for 30 minutes. For the electron transport layer, a dense titanium dioxide layer of approximately 40 nm was deposited by spray pyrolysis of a solution containing 0.6 mL of di(acetylacetonate)titanate and 0.4 mL of acetylacetone in 2-propanol (7 mL) at 450 °C, followed by UV-ozone treatment for 15 minutes. The dense titanium dioxide film was then immersed in a 5 mM butyltrimethoxysilane solution in isopropanol for 3 hours to perform strain release layer modification, suppressing lattice distortion at the buried interface of the film. Afterward, the substrate was rinsed in isopropanol and then dried under a nitrogen stream. For the CsPbI3 active layer, a 0.6 M solution of stoichiometric CsI, PbI2, and DMAI in a 1:1:1.3 molar ratio was prepared in N,N-dimethylformamide. For the CsPbI3 precursor solution, the precursor solution was cast onto the substrate and then spin-coated at 2800 rpm for 30 s, followed by thermal annealing at 215 °C for 4.5 min. For the surface halide substitution treatment, DMAI was dissolved in isopropanol at a concentration of 15 mM and spin-coated at 5000 rpm for 30 s, followed by annealing the film stack at 210 °C for 1 min. All annealing processes were performed in a drying oven with humidity controlled at 23-25%. Subsequently, a hole transport layer was deposited on top of the active layer by spin-coating a PTAA solution at 3000 rpm for 30 s. The PTAA solution was prepared by spin-coating PTAA (12 mg / ml)... -1 Dissolve in toluene and add 6 μL of Li-TFSI (340 mg / ml). -1 The solar cell was prepared using acetonitrile solution and 6 μL of 4-tert-butylpyridine; finally, a 100 nm thick gold top electrode was deposited by vapor deposition. The effective area (0.16 cm²) was used. 2The mask was used to deposit 100 nm and 200 nm magnesium fluoride layers on the glass surface of the FTO substrate and the gold surface of the device, respectively, as anti-reflection layers and initial protective layers. Example 2
[0027] The process is basically the same as in Example 1, except that for the surface halide substitution treatment, DMABr is dissolved in isopropanol at a concentration of 15 mM and spin-coated at 5000 rpm for 30 s, and then the film stack is annealed at 210 °C for 1 minute. Example 3
[0028] The process is basically the same as in Example 1, except that for the surface halide substitution treatment, DMACl is dissolved in isopropanol at a concentration of 15 mM and spin-coated at 5000 rpm for 30 s, and then the film stack is annealed at 210 °C for 1 minute.
[0029] Comparative Example 1
[0030] The results are basically the same as in Example 1, except that no surface halide substitution treatment was performed, i.e., the CsPbI3 film was not treated with DMAX (X = Cl or Br).
[0031] Figure 1 A schematic diagram of halide substitution on the surface of CsPbI3 perovskite after treatment with DMAX (X = Br or Cl) salt, as shown below. Figure 1 As shown, when the CsPbI3 perovskite surface is modified with DMAX (X = Br or Cl) salt, Br - and Cl - I-replacing the surface of CsPbI3 thin film - A gradient of inorganic perovskite components, CsPbI, is formed on the perovskite surface. 3-y X y (X = Br or Cl) reduces the lattice size and generates residual compressive strain along the film.
[0032] Figure 2 The diagram shows the relationship between the peak position of the (110) plane of CsPbI3 extracted from the grazing incidence X-ray diffraction pattern and the change of different X-ray incident angles, which more clearly shows the substitution of halides on the film surface.
[0033] Figure 3 The JV curves of Comparative Example 1 and Examples 1, 2, and 3 show that the open-circuit voltage of Comparative Example 1 and Examples 1, 2, and 3 has a significant upward trend. Therefore, the photoelectric efficiency of Examples 1, 2, and 3 is higher than that of Comparative Example 1. Among them, Example 3 has the highest photoelectric efficiency, reaching 21.2%. Example
[0034] The tandemly connected modules were obtained by laser structuring using a laser scribing system equipped with a 1064 nm laser with a maximum power of 20 W, interconnecting P1, P2, and P3. A 50 μm scribing width was achieved by laser scribing the P1 line on an FTO substrate using 10 W power, a 100 ns pulse width, and a 100 kHz repetition rate. The substrate was then sequentially cleaned with detergent, acetone, and isopropanol for 15 minutes each, followed by nitrogen drying. The FTO was then subjected to UV-ozone treatment for 30 minutes. A titanium dioxide layer and a strain-releasing layer were deposited onto the single cell using the same method as in Example 1. A CsPbI3 precursor solution was doctor-coated onto the ITO glass substrate covered with the titanium dioxide and strain-releasing layers at a speed of 30 mm / s and a gap of 200 μm, using a nitrogen knife operating at 25 psi during doctor-coating. The wet film was then annealed at 215 °C for 4.5 minutes. For surface halide substitution treatment, a 20 DMACl solution was blade-coated at a speed of mm / s and a gap of 150 μm, and the stack was then thermally annealed at 210 °C for 1 min. PTAA solution was then blade-coated at a speed of 15 mm / s and a gap of 200 μm. For the deposited layer, the P2 line was laser-etched with a power of 6 W, a pulse width of 100 ns, and a repetition rate of 70 kHz to obtain a 150 μm etch width. Gold (100 nm) was then deposited as an electrode. The P3 line was laser-etched on the electrode using a power of 6 W, a pulse width of 100 ns, and a repetition rate of 70 kHz to obtain a 100 μm etch width. 100 nm and 200 nm magnesium fluoride layers were deposited on the glass surface of the FTO substrate and the gold surface of the device, respectively, as anti-reflection layers and initial protective layers. The geometry fill factor was approximately 0.93.
[0035] Figure 4 The efficiency champion device in Example 4 (effective area 23.9 cm²) 2 The JV curve and power curve (with a geometric fill factor of approximately 0.93) show that the photoelectric efficiency of the large-area champion device is as high as 19.2%, indicating that the technology of this invention can be effectively applied to large-area modules.
[0036] Figure 5 The graph shows the normalized photoelectric efficiency versus aging time for the packaged devices prepared in Comparative Example 1 and Examples 1, 2, and 3 under constant sunlight irradiation at maximum power output in air at 40°C. Comparative Example 1 showed an initial efficiency decrease of over 20% after 1000 h. In contrast, Example 1 exhibited significantly enhanced operational stability due to surface passivation effects. 80With a lifespan of 2400 hours, in stark contrast, the efficiency of Example 2 remained above 90% of its initial efficiency after 3200 hours of operation, while the efficiency of Example 3 showed negligible initial efficiency loss (less than 1%) after 3200 hours of continuous operation.
[0037] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make corresponding changes and adjustments to the technical approach of the present invention without departing from the basic principles of the present invention, and such changes and adjustments all fall within the protection scope of the present invention.
Claims
1. A method for preparing an inorganic perovskite solar cell based on surface halide substitution, characterized in that, CsPbI3 films were treated with DMAX dimethylamine halide solution and then annealed. The annealing process drove the crystallization of the CsPbI3 film while simultaneously removing DMA by evaporation. + To ensure the purity of the CsPbI3 film composition, DMAX reacts only with the film surface, causing its surface composition to transform into a mixed halide CsPbI3. 3-y X y Where X is Br or Cl, when I - smaller Br - or Cl - During substitution, a gradient of inorganic perovskite components CsPbI is formed on the perovskite surface. 3-y X y The reduction in lattice size and the resulting surface halide substitution cause lattice contraction, thereby inducing equivalent compressive strain near the perovskite surface. The uniformly distributed compressive strain along the film effectively passivates the surface halide vacancies, which helps stabilize the phase state of the CsPbI3 perovskite film and suppresses photoinduced ion migration.
2. The method for preparing inorganic perovskite solar cells based on surface halide substitution according to claim 1, characterized in that, The concentration of the dimethylamine halide solution is 0.5-2 mM.
3. The method for preparing inorganic perovskite solar cells based on surface halide substitution according to claim 1 or 2, characterized in that, The solvent for the dimethylamine halide solution is isopropanol, N,N-dimethylformamide, or dimethyl sulfoxide.
4. The method for preparing inorganic perovskite solar cells based on surface halide substitution according to claim 1 or 2, characterized in that, The dimethylamine halide solution was spin-coated onto the perovskite film surface at a rotation speed of 3000-6000 rpm.
5. The method for preparing inorganic perovskite solar cells based on surface halide substitution according to claim 1, characterized in that, The annealing temperature is 100-300℃, and the annealing time is 1-10 minutes.
6. The method for preparing inorganic perovskite solar cells based on surface halide substitution according to claim 1, characterized in that, The core functional layer of the solar cell has a formal structure or an inverse structure.
7. The method for preparing inorganic perovskite solar cells based on surface halide substitution according to claim 6, characterized in that, The formal structure, from the substrate upwards, consists of an electron transport layer, a perovskite light-absorbing layer, and a hole transport layer; the inverse structure, from the substrate upwards, consists of a hole transport layer, a perovskite light-absorbing layer, and an electron transport layer.
8. An inorganic perovskite solar cell based on surface halide substitution, characterized in that, Prepared using the method described in any one of claims 1-7.