Solution-Processed Kesterite Cu2znsns4 As Efficient Hole Extraction Layer For Inverted Perovskite Solar Cells

The hole extraction layer (HEL) plays a critical role in determining the charge extraction in inverted perovskite solar cells (PSCs) besides affecting the perovskite crystallization. Herein, we demonstrate efficient inverted perovskite solar cells based on solution-processed kesterite Cu2ZnSnS4 (CZTS) as the HEL for the first time. We achieved CZTS HEL with desired phase purity and optimal film coverage by optimizing the spin-coating process. Moreover, photoluminescence (PL) studies indicate that the CZTS HEL developed in this work provides superior hole extraction in comparison with the widely reported NiOx. This ultimately results in a respectable power conversion efficiency of 13.75% for the proof-of-concept device, reaching a level that is comparable to that of the NiOx-based device.