Preparation And Photovoltaic Property Investigation Of CsPbIBr₂ Inorganic Perovskite Solar Cell

In recent years,CsPbIBr₂ inorganic perovskites have attracted much attention from the photovoltaic community due to their suitable band gap and excellent stability.However,because of the limited solubility of bromide and the difficulty of volatilization of the high-boiling polar solvent dimethyl sulfoxide(DMSO),the prepared CsPbIBr₂ films have fine grains,more holes and defects.The poor film quality will lead to a short carrier diffusion distance,which greatly reduces the photovoltaic performance of the device and seriously hinders its further development.To address these problems,this dissertation firstly used Cl^-doping to increase the perovskite grain size and improve the crystalline properties of the film,and adopted a simple one-step solution method to prepare high-quality CsPbIBr₂films.Meanwhile,a new method of alcohol-induced solvent engineering was developed to accelerate its rapid crystallization,resulting in pinhole-free and highly crystallined CsPbIBr₂films.Finally,inverted CsPbIBr₂ perovskite solar cells(PSCs)were prepared in view of the hysteresis of regular perovskite devices and the high cost of Spiro-OMe TAD hole transport materials(HTM).The main research contents of the thesis were as follows:Firstly,study on the performance of Cl^-doped CsPbIBr₂ inorganic perovskite films and devices.According to the content of Pb Cl₂ in the precursor solution,the doping amount of Cl^-in Cs Pb IBr_2-xCl_x perovskite films was adjusted,and then Cs Pb IBr_2-xCl_x films were obtained by solution-based spin-coating method.Studies shown that the introduction of Cl^-would not change the phase structure,and with the increase of Cl^-content,the optical band gap,the light absorption intensity,and the crystallinity all increased,and the grain orientation is significantly improved;at the same time,the grain size increased,the surface coverage increased,and the number of defects and grain boundaries decreased significantly.It was found that the doping of 10%content of Pb Cl₂ could increase the efficiency of CsPbIBr₂ devices from 8.48%to 9.38%.Secondly,fabrication of CsPbIBr₂ inorganic perovskite films by solvent engineering and its device performance study.First of all,some low-boiling alcohols,such as methanol,ethanol,etc.,were added to form a low-boiling DMSO-alcohol azeotropic mixture,which can volatilize quickly and accelerate the crystallization process of CsPbIBr₂ films effectively.Also,Cs I additives were used to suppress the inherent self-doping and passivate defects of perovskite.In addition,the effect of annealing temperature on film quality and device performance was also studied.It was found that CsPbIBr₂films with large grains,no pinholes,and(100)crystal orientation could be obatined by Cs I/methanol treatment and annealing at 280?,thus successfully achieved11.49%high-efficiency inorganic perovskite photovoltaic devices.Thirdly,research on CsPbIBr₂ inverted inorganic perovskite cell based on BCP interface modification.By inserting a small organic molecule bath copper spirit(BCP)between the electron transport layer and the electrode,the inverted perovskite solar cell with a structure of FTO/Ni O_x/CsPbIBr₂/PCBM/BCP/Ag was fabricated.The device modified by the BCP interface had a lower density of trap states,which also effectively improved the photovoltaic device performance.Through the BCP interface modification,the efficiency of the CsPbIBr₂ perovskite cell device was greatly increased from 1.69%to 7.18%,and the steady-state output efficiency was 7%.In addition,the forward and reverse scan hysteresis factor of the device was only 1.4%,almost without hysteresis effect.