Component Engineering And Photoelectric Performance Study Of Lead-free Perovskite

So far,the conversion efficiency record of single-junction perovskite solar cell has reached 23.7%,which has already exceeded efficiency record of polycrystalline silicon solar cell.However,the light absorbing layer used in used in the current high-efficiency perovskite battery is based on lead.As we know,lead,as a heavy metal element,can easily cause great damage to the human body and the environment.Therefore,some researchers began to look for substitution for lead.Up to now,tin is the best choice,tin-based solar cell’s efficiency is close to 10%,has good development potential.Further more,the inorganic tin-based perovskite is less toxic and environmentally friendly than the organic-inorganic hybrid tin-based perovskite.For an excellent light absorbing perovskite film,it should have the right film properties.In terms of thickness,it is necessary to combine the transport of carriers and the absorption of sunlight.It should be neither too thick nor too thin.In addition,the film should have good crystallinity and other properties.This article adjusts the spin coating process,annealing process,battery structure and so on.Finally,spinning at 8000 rpm for1 minute（10 s dropwise addition of chlorobenzene）,annealing at 80°C for 5 min,using ITO/PEDOT:PSS/PVK/PC61BM/BCP/Al battery structure,the device achieved the best efficiency of 2.88%.For photovoltaic perovskites,the regulation of the X-site composition is particularly important.Controlling proportional regulation of iodine and bromine is a more common way to adjust the band gap of perovskites.As early as in the research of Pb-based perovskite MAPbI3 solar cells,it is possible to increase the stability of perovskites and reduce the grain boundaries in the film by doping a small amount of Cl to the halogen site to increase the perovskite grain.Take the S-Q curve into consideration,this paper first sets the appropriate ratio of I and Br to adjust the band gap of the all-inorganic Sn-based perovskite to a suitable interval for solar cells.Then,different amounts of Cl are doped into perovskite.The doping amount of Cl is adjusted from 0%to 10%,so that the band gap of the perovskite film is adjustable from 1.34 eV to 1.58 eV.In addition,the doping of Cl also suppresses the oxidation of Sn²⁺to improves the stability of the perovskite.When the Cl doping amount is 3.3%,the voltage of the device is increased while the current density is not lowered,and the highest efficiency is obtained.