Visualized acid–base discoloration and optoelectronic investigations of azines and azomethines having double 4-[N,N-di(4-methoxyphenyl)amino]phenyl terminals†
Abstract
Two small molecular chromogenic sensors (azine MS-1 and azomethine MS-2) were synthesized for acid–base discoloration and optoelectronic investigations. It was found that the color of both sensors in solution and in the solid state changed obviously from yellow to purple and blue after treatment with acid, which could be easily detected by the naked eye. Furthermore, single-crystal conductance of MS-1 and MS-2 could be significantly enhanced after treatment with HCl gas flow. On the other hand, MS-2 showed relatively good film-forming ability and could be used as a hole transport material (HTM) in perovskite solar cells, exhibiting a power conversion efficiency (PCE) of 6.68%. To the best of our knowledge, this is the first demonstration of perovskite solar cells including a HTM based on a low-cost Schiff-base.