Study On Optimization Of Perovskite Film And Its Device Performance Based On Vapor Phase Two-step Method

With the increasing proportion of photovoltaic power generation technology in green energy,solar cells are currently becoming a research hotspot,the main direction of which is the improvement of device photoelectric conversion efficiency and service life.Organic-inorganic hybrid perovskite has become one of the most promising photovoltaic materials for solar cells because of its excellent properties such as suitable and adjustable band gap width,wide light absorption range,and high carrier mobility.With the continuous deepening of research on perovskite solar cells,the problems of uneven thickness of perovskite thin films,poor device stability,and difficulty in large-area preparation are urgently to be resolved.Based on the improved two-step vacuum vapor deposition method of perovskite thin film preparation process proposed by our team,the following work has been carried out to improve the efficiency and stability of perovskite solar cells:First,the vacuum evaporation method was used to prepare the Pb I₂ film,and then the single source flash evaporation method was used to rapidly evaporate MAI?CH₃NH₃I?on the Pb I₂film and anneal it to form the MAPb I₃ perovskite film through solid-solid reaction.The effects of process parameters such as Pb I₂ evaporation rate,evaporation thickness,and perovskite annealing temperature on the crystallization quality of the film were explored to prepare a uniform and dense MAPb I₃ perovskite film.The perovskite films were used as active layers to prepare MAPb I₃ perovskite solar cells with p-i-n inverted planar heterojunc-tion structure by full evaporation,and the relevant process parameters of hole transport layer and electron transport layer were optimized.The photoelectric conversion efficiency of solar cell devices with an effective area of 0.07 cm² was 14.06%.Secondly,based on the previous research,the Cs I was introduced into the preparation of Pb I₂film by dual-source co-evaporation to obtain a dual Cs_xMA_1-xPb I₃ film.By adjusting the evaporation rate ratio of Cs I and Pb I₂,when the Cs⁺content in the perovskite film is 5%?x=0.05?,the photoelectric conversion efficiency of the prepared Cs_0.05MA_0.95Pb I₃ device is17.15%,which is 20%higher than that of the MAPb I₃ device.Under the unencapsulated condition,the Cs_0.05MA_0.95Pb I₃ device is exposed to air with a relative humidity of 40%for half a month,and the device efficiency attenuation is only 15%,which is better than the MAPb I₃ device with an equivalent conditional efficiency attenuation of 35%.Experiments show that Cs⁺doping can effectively reduce the defect density of perovskite films and improve the uniformity and stability of the films.Finally,based on the above work,the application of Cs_0.05MA_0.95Pb I₃ film in large-area perovskite solar cell modules was explored.A large-area module device with an effective area of 10.8 cm² was fabricated,and its photoelectric conversion efficiency can reach10.24%,which lays a foundation for further advancing the application of perovskite photovoltaic devices.