Dopant‐Free Hole‐Transporting Material with Enhanced Intermolecular Interaction for Efficient and Stable n‐i‐p Perovskite Solar Cells

Abstract

Abstract Developing low‐cost, efficient, and stable dopant‐free hole‐transporting materials (HTMs) in perovskite solar cells (PVSCs) is essential to their commercial deployment. Herein, the synthesis of a novel spirofluorene‐dithiolane based small molecular HTM, SFDT‐TDM, through facile and low‐cost synthetic routes is reported. The CH … π interactions in adjacent SFDT‐TDM are beneficial for high hole mobility and the methylthio groups in SFDT‐TDM can serve as Lewis bases to passivate the defects on the surface of perovskite films, leading to suppressed non‐radiative recombination and enhanced charge extraction at the perovskite/HTM interface. As a result, Cs x FA 1− x PbI 3 based PVSCs with SFDT‐TDM as the HTM realize champion power conversion efficiencies (PCEs) of 21.7% and 20.3% for small‐area (0.04 cm 2 ) and large‐area (1.0 cm 2 ) devices with negligible photocurrent hysteresis, respectively. Additionally, all‐inorganic CsPbI 3− x Br x based PVSCs with SFDT‐TDM demonstrate an impressive PCE of 17.1% along with excellent stability. This work highlights the great potential of the spirofluorene core for exploring low‐cost and dopant‐free HTMs for PVSCs with high efficiency and stability.