Origin of enhanced stability in thiocyanate substituted α-FAPbI3 analogues

• 来源期刊: 中国科学:化学（英文版）
• 年，卷（期）: 2019,（7）
• 页码范围: 866-874
• 页数: 9页
• 语种: 英文

摘要

In the past few years,hybrid perovskites have emerged as the most promising photovoltaic materials due to their excellent optoelectronic properties,and easy fabrication methods.However,the long-term stability is still the main obstacle for their commercial applications.Recently,thiocyanate-doped hybrid perovskites have shown enhanced stability and impressive efficiency,but the reason is still unknown.Herein,we discussed the enhanced stability of SCN-substituted pseudocubic FABX3 (B=Pb2+,Sn2+;X=I-,Br-,and Cl-) based on the density functional theory.Through a series of calculations of Bader charge transfer,vacancy formation energies of different kinds of vacancies,decomposition enthalpy,phonon density of states,and ab initio molecular dynamics simulation,we conclude that the incorporation of SCN-can stabilize pseudocubic FABX3,and attribute the enhanced stability mainly to two factors:(1) the strong interaction between pb2+/Sn2+ and SCN-,as well as the strong hydrogen bonding between FA+ and X/SCN-,and (2) the structural tilting induced by the incorporation of SCN-.These findings provide alternative method for tuning the poor stability of pseudocubic FABX3,as well as for obtaining high-performance solar cells.