Probing Pathways of Conductive Filaments of FAMAPbI3with Controlled FA Composition Using Conductive Atomic Force Microscopy

Abstract

The characteristics of FAMAPbI3-based write-once-read-many (WORM) devices were controlled by a cation-exchange process as part of a technique to alter the FA composition in FAMAPbI3 films. Interestingly, it was found that an increase in the FA composition in FAMAPbI3 films resulted in a completely inactive WORM device. Such a memory characteristic of a WORM device was attributed to the high iodine vacancy (VI) ion migration energy that prevented the formation of VI conductive filaments (CFs) with the increase in the FA composition in FAMAPbI3 film. By comparing the active and inactive FAMAPbI3 WORM devices, the pathways of CFs within FAMAPbI3 WORM devices were investigated using conductive atomic force microscopy. Our results showed that the CFs were dominantly formed around grain boundaries, while some grain interior regions showed very low conductivity. These studies on the CF formation mechanism provide a better understanding of RS memory characteristics in multication perovskite materials.