Additives Enhance The Optoelectronic Properties Of Perovskite Cells

Solar cells using metal halide perovskites as absorption materials are currently the most promising photovoltaic power generation technology.The efficiency of perovskite solar cells has rapidly increased from 3.8%in 2009 to 25.5%now.This excellent performance is based on the excellent photoelectric semiconductor performance of metal halide perovskites.It has excellent defect tolerance,high carrier mobility,balanced electron and hole transport performance,high visible light absorption coefficient,adjustable direct band gap,long carrier diffusion length and special bipolarity.Therefore,the perovskite solar cell can excellently complete the process of absorption of incident light,excitation,diffusion,separation and collection of photo-generated carriers.However,the performance of perovskite solar cells has dropped sharply due to the combined effects of humidity,light,temperature and oxygen in the natural environment.Additives are an effective method to control perovskite crystallization,prepare high-quality films and passivate defects.This paper mainly studies the influence of additives on perovskite solar cells.The main results are as follows:(1)Ionic-liquids(IL),for their unique physicochemical properties including large electrical conductivity,high carrier mobility,good thermal stability,etc.,have been widely used in batteries,supercapacitors,actuators,and organic solar cells.We use an ionic liquid 1-allyl-3-methylimidazolium-chloride to passivate all-inorganic CsPbI2Br perovskite filmshort,which promotes the better growth of the CsPbI2Br perovskite film,improves the crystallinity and grain size.At the same time,it also inhibits the generation of ?-CsPbI2Br phase,the generation of defects and the recombination of carriers,and improves the efficiency of charge extraction.Based on the control device,the open circuit voltage(Voc)is 1.24 V,the short-circuit current density(Jsc)is 15.25 mA/cm2,the fill factor(FF)is 78.43%,and the PCE is significantly improved to 14.89%,which still has an efficiency exceeding 85%after 25 days.(2)When using 1-allyl-3-methylimidazolium chloride to improve the pure FAPbI3 perovskite solar cell system that is deeply affected by the humidity in the environment.We found that it can passivate the surface of the film,promote the formation of?-FAPbI3 phase,and inhibit the appearance of ?-FAPbI3 phase and the precipitation of lead iodide.The FAPbI3 perovskite layer has micron-sized grains,and the white spots on the surface of the perovskite film have all disappeared.Significant improvement in the quality of perovskite films can increase the charge collection capacity and efficiency.The best-performing device has an open circuit voltage of 1.10 V,a short-circuit current density of 25.50 mA/cm2,a fill factor of 73.82%,an efficiency of 20.79%,and it remains above 87%after 24 days.(3)By adding benzethonium chloride to the FA0.92Cs0.08PbI3 perovskite precursor solution to inhibit the formation of ? phase and promote the formation of a phase,we found that the grain size of the modified perovskite film increases,the white spots on the surface disappear,and the hydrophobicity of the film is significantly enhanced.Therefore,the modified FA0.92Cs0.08PbI3 perovskite solar cell has an open circuit voltage of 1.07 V,a short-circuit current density of 24.86 mA/cm2,a fill factor of 79.53%,and an efficiency of 21.07%,and it remains above 95%after 25 days.