1T-Rich 2D-WS2 as an interfacial agent to escalate photo-induced charge transfer dynamics in dopant-free perovskite solar cells

Abstract

The scientific surge in halide perovskite solar cells (PSCs) is due to their solution processability and high power conversion efficiency; however, the deficiency in the photo-induced charge transfer dynamics at the perovskite-charge transport layer interfaces due to depleted energy alignment and surface traps impedes performance improvement. Interface engineering has become one of the rewarding approaches to control the charge accumulation and recombination at interfaces, which in turn promotes excellent charge extractability and device performance. Here, we introduce a few-atom thick 1T-rich 2D-WS₂ as an interfacial layer placed on a perovskite to minimize the energy barrier and charge accumulation at the interface to intensify the extraction of detrapped charges and charge transfer dynamics. By combining the interfacial layer in a dopant-free hole transport layer, we achieved a stabilized efficiency of over 19% with a significantly enhanced open-circuit voltage and fill factor. Our work put forward the deep experimental understanding of 2D materials as an interfacial agent toward their stabilized performances.