Stable Perovskite Solar Cells based on Hydrophobic Triphenylamine Hole‐Transport Materials

Abstract

AbstractTwo hole‐transporting materials (HTMs) based on N,N,N′,N′‐ tetraphenylbenzidine (TPB) and MeO‐triphenylamine (MOTPA) are synthesized. The HTMs offer outstanding thermal stability, film‐forming properties, and hole mobilities. Perovskite solar cells (PSCs) are prepared using either pristine HTM layers or layers doped with cobalt salts. The nondoped PSCs with as‐synthesized HTMs show better performance compared to spiro‐OMeTAD, especially for long‐time stability in ambient air. The power conversion efficiency (PCE) of the cells decreases by only 3 % after 600 h of storage. The nondoped hole‐transport layer (HTL) are hydrophobic, with a contact angle of 94.3° to water. The moisture‐repelling ability of these HTMs are demonstrated by exposing the nondoped PSCs to an atmosphere saturated with water vapor. The PCE of doped PSCs with spiro‐OMeTAD as HTL decreased 53 %, while that of nondoped PSCs with the as‐synthesized HTMs as HTL only decreased 27 % after 15 min. These result thus show a new method to improve the operational stability of PSCs, especially at high humidity levels.