Study On Syntheses And Properties Of CsPbX₃(X=I?Br) Perovskite Thin Films

During the past 10 years,organic-inorganic hybrid perovskite has attracted great attention,especially in the field of solar cells,the photoelectric conversion efficiency has exceeded 25%in just a few years.However,due to the volatility and hygroscopicity nature of organic cations,organic-inorganic hybrid perovskite suffers from chemical instability.Therefore,CsPbX₃(X=I,Br)is considered as the most promising candidate for high performance perovskite devices due to its good thermal stability and adjustable band gap.However,it still faces some challenges in practical application,because CsPbX₃ perovskite will spontaneously change into non-perovskite phase at room temperature.How to prepare all inorganic perovskite with great stability in room temperature has become a research hotspot.In this thesis,the effects of different X-site components on the photoelectric properties of CsPbX₃ perovskite materials were studied.Based on this,the properties of the CsPbX₃ perovskite materials were further regulated and optimized.For CsPbBr₃,due to its excellent stability and resistance properties,we applied it to memristors,and adjusted the morphology of the films by adding butyric acid for post-treatment to successfully prepare a series of high-quality thin films with big grains larger than 800 nm.The memristors based on such CsPbBr₃ thin films exhibit typical bipolar resistive switching behavior and remarkable characteristics such as high R_on/R_off ratio about 10³,very low working voltage about 0.7 V.Furthermore,through controlling the addition of butyric acid,memristors with multilevel resistive switching can be easily prepared.For CsPbI₂Br,we added a small amount of?-aminobutyric acid to the precursor solution,successfully overcome two shortcomings such as high annealing temperature and poor phase stability,and prepared high-quality perovskite films at a temperature far below the phase transition temperature.The photoelectric conversion efficiency of solar cells based on this reaches 11.20%,which is improved by 32.39%,and corresponding device maintains the initial efficiency of 70%after 10 days without encapsulation;Further,for CsPbl₃,we added the ascorbic acid to the perovskite material in the same way,successfully overcome the shortcoming of poor stability at room temperature,and prepared high-quality CsPbl₃perovskite films with long-term stability.The photoelectric conversion efficiency of solar cells based on this reaches 11.44%,and corresponding device maintains the initial efficiency of 76%after 10 days without encapsulation.