Study On The Fabrication Of Perovskite Solar Cells Via Step-by-step Method

Organic-inorganic hybrid Perovskite solar cells draw much attention in photovoltaic field owing to the low preparation cost,simple preparation process and high photoelectric conversion efficiency.In the past decade,the efficiency of Perovskite solar cells has increased rapidly,showing the promising application prospects.However,most of the breakthroughs in the efficiency of perovskite solar cells have been achieved only in a single cell with a small area in the laboratory,which is still a large gap to the commercial application of large-area perovskites.The adjustable manufacturing process and high-quality film quality are the keys to improving the performance of perovskite solar cells.Therefore,in this paper,the step-by-step spin coating method is applied to fabricate perovskite film,and the solvent engineering strategy and intermediate state film processing methods are used to improve the film quality and device performance.Then,above optimization strategy is applied to prepare large-area perovskite solar cells via the step-by-step plastic coating method.The main contents of this dissertation are as follows:(1)Study on the performance of perovskite films and solar cells prepared by ligand solvents.Three ligand solvents NMP(N-methylpyrrolidone),DMSO(dimethyl sulfoxide),and DMI(1,3-dimethyl-2-imidazolinone)were selected to investigate the influence of bonding ability of the Pb-O bond formed by Lead iodide and different solvents on the perovskite grain size,defect density,and device performance by adjusting the solvent composition in the perovskite precursor solution.The results show that DMSO and DMI exhibit a stronger coordination effect than NMP,and can prepare perovskite films with larger grain sizes and fewer defects,thereby reducing the carrier recombination and improving charge mobility.The photoelectric conversion of the two devices based on DMSO and DMI are 19.99%and 20.69%,respectively,and the DMI-based perovskite film shows the better thermal stability.(2)Study on the performance of perovskite films and solar cells prepared by the cooling treatment of intermediate film.The cooling treatment of intermediate film to control the nucleation and crystallization of perovskite films was proposed.The perovskite intermediate film prepared by two-step spin coating is cooled.Due to the lower temperature,the procedure of intermediate phase transferring to perovskite?phase is found to be delayed.the nucleation rate is reduced,the reaction between lead salt and organic salt is more sufficient,and the perovskite films with larger grain size and fewer defects are obtained.The final perovskite device prepared based on the cooling treatment shows a photoelectric conversion efficiency of 21.51%,which has good repeatability and stability.The photoelectric conversion efficiency of the unencapsulated perovskite solar cell still maintains 83%of the initial efficiency in a dark environment(humidity 20%)for 30 days.(3)Study on the performance of perovskite films and solar cells prepared by step-by-step plastic coating method.The injection speed of the plastic coating is adjusted to improve the quality of the large-area perovskite film,and the optimized process(discussed in Unit 2)is applied to the preparation of large-area perovskite solar cells.Finally,the large-area perovskite solar module with 11.7%photoelectric conversion efficiency was successfully fabricated on a 4×4 cm~2 substrate(active area:7.2 cm~2).