Ultra-small interlayer spacing and nano channels in anionic layered perovskite Cs2Pb(SCN)2I2 enable efficient photoelectric conversion

Abstract

Due to distinctive lattice and electronic properties, the thiocyanate anion (SCN−) perovskite as an alluring two-dimensional (2D) material system, can be applied in optoelectronic devices. Herein, both photovoltaic and photodetection performances of the 2D Cs2Pb(SCN)2I2 have been investigated. Compared with the conventional cationic 2D perovskites, Cs2Pb(SCN)2I2 possesses ultra-small interlayer spacing, additional interlayer nano channels, which is thus beneficial for charge transport ability. The planar heterojunction solar cell based on Cs2Pb(SCN)2I2 as the light absorber, has presented the highest power conversion efficiency among long-chain-cation-based 2D perovskite devices. Besides, the Cs2Pb(SCN)2I2-based photodetector also exhibits much higher photodetection performance (i.e. quantum efficiency, on/off ratio, responsivity, detectivity, response speed, polarization sensitivity and detection stability). It is thus suggested that these outstanding photoelectric characteristics of Cs2Pb(SCN)2I2 could bring huge opportunities for its more abundant optoelectronic applications, such as field-effect transistor and light-emitting diodes.