Friction characteristics of two-dimensional hybrid organic-inorganic perovskites at the nanoscale

Abstract

Two-dimensional (2D) hybrid organic-inorganic perovskites (HOIPs) have attracted a great deal of interests due to their remarkable photovoltaic properties providing high power conversion efficiency. To achieve reliability for the applications of 2D HOIPs, understanding of friction characteristics is essential. However, the fundamental friction characteristics of 2D HOIPs are not clearly understood yet. Therefore, a more thorough study of friction characteristics of atomically thin 2D HOIPs is needed. In this work, the thickness-dependent friction characteristics of 2D HOIPs were quantitatively investigated using atomic force microscopy (AFM) under various normal forces to determine the frictional behaviors. Three types of 2D HOIPs with different organic chain length were used to investigate the effect of the organic chain length on friction characteristics, and also the effect of the number of layers was examined. The results showed thickness-dependent behavior on the friction characteristics at the nanoscale and the effect of chain length becoming less significant with increasing the number of layers. These results may help to gain a fundamental understanding of friction characteristic of atomically thin 2D HOIPs, so that the results might contribute to broadening their applications.