Preparation Of Lead-free Perovskite Materials And Performance Optimization Of Solar Cell Devices

The perovskite solar cell has been developed for nearly a decade,and the solar conversion efficiency has achieved 25.2%.Because of its low cost and simple preparation method,its commercial application has the potential to surpass the silicon-based solar cell.However,current high-efficiency perovskite solar cells contain metal Pb,and there is a risk of leakage.More and more researchers are devoted to the development of non-lead perovskite materials,among which Sn-based perovskite and Ge-based perovskite have theoretically excellent potential,and the solar energy conversion efficiency is also increasing year by year.At present,the efficiency of Sn-based perovskite has reached 13.24%.This paper mainly studies and optimizes the FA_0.75MA_0.25Sn I₃perovskite battery device,and explores the preparation methods of pure inorganic lead-free broadband perovskite Cs Sn Br₃ and Cs Ge I₃.The specific research contents are as follows:?1?The FA_0.75MA_0.25Sn I₃ perovskite thin film was prepared by a one-step method.By adjusting the concentration of Sn F₂ additive and the concentration of the precursor solution to optimize the preparation process,the Sn F₂ concentration was optimized to be 10 mol%compared to Sn I₂,and the concentration of the precursor solution was optimized to 1 mol/L.By treating PEDOT:PSS substrate with 0.5 mol/L acetamide,the perovskite crystallinity was improved,carrier recombination was inhibited,and the carrier transmission efficiency between the interfaces was improved.The average efficiency of the 16 groups of devices was increased by 28%.The best device efficiency reaches 4%.?2?Sn powder is used to reduce the content of Sn⁴⁺ions in the precursor,so that cheap and low-purity Sn I₂ can be used to prepare perovskite.The device efficiency is comparable to that of high-purity Sn I₂.The optimal device efficiency is 3.10%.The studies have shown that the presence of excessive Sn⁴⁺will not only produce more defects,but also affect the normal combination of Sn²⁺and organic halides.The flocs formed by Sn⁴⁺and organic halides could hinder the transport of carriers,Adding Sn powder to the precursor can effectively reduce this kind of situation.?3?The preparation of Cs Sn Br₃ perovskite films and powders with ethanol/ethylene glycol as a solvent has a greater degree of crystallinity than the films and powders prepared with DMF/DMSO as a solvent,and the perovskite is preferentially oriented to the?100?crystal plane.Moreover,the powder prepared by ethanol/ethylene glycol has better absorption performance.In addition,by optimizing the reaction conditions,the use of hypophosphorous acid to reduce Ge⁴⁺yielded high-purity Cs Ge I₃ perovskite powder.