Pressure Tuning of the Mixed Conduction and Light Response in Organolead Tribromide Perovskites and Organolead Iodine Perovskites

Abstract

Ion migration in organometal trihalide perovskites (OTPs) has been attracting extraordinary attention after the report of current-voltage hysteresis in OTPs based solar cells. Ionic transport is suggested to be an important factor that contributes to the stability and performance of OTPs based devices. Recent scientific studies on organic–inorganic hybrid perovskites mainly focus on the ion migration behaviors at ambient conditions. However, how external conditions affect the properties of OPTs is seldom studied. In this work, we have conducted high pressure in situ alternating current impedance spectroscopy, X-ray Diffraction, and photocurrent measurements on both MAPbI₃ nanorods and polycrystalline MAPbBr₃ at room temperature. Some interesting results have been observed including the pressure-induced new structures, the bulk dominant electrical transportation property, the pressure-enhanced photoelectric response, and the pressure tuning of mixed electron/ion conduction behaviors. From the high-pressure investigations, we can be inspired that the power conversion efficiency of OPTs based devices can be improved via inducing the artificial stress, such as chemical doping and lattice-mismatched thin films fabricating.