Crystallization control of wide-bandgap perovskites for efficient solar cells via adding an anti-solvent into the perovskite precursor

Organic-inorganic halide-based wide-bandgap perovskite solar cells (PSCs) have been researched extensively due to their potential application in tandem solar cells. In this study, we directly added an anti-solvent (diethyl ether, DE) into the perovskite precursor for controlling the crystallization process of perovskite layers with a wide bandgap (1.74 eV). The introduction of DE could facilitate the nucleation and accelerate the perovskite growth during the spin-coating process. Due to the improved crystallization of the perovskite, the wide-bandgap PSCs showed a high power-conversion efficiency (PCE) of 19.7% on average with improved current density and fill factor. In contrast, the control devices without using DE exhibited a low average PCE of 17.6%. Moreover, the ambient stability of the related PSCs was simultaneously enhanced with a remarkably decreased PCE degradation, from 31.3% to 16.8%, after 16 days of storage and measurement. The DE-assisted well-crystallized PSCs showed a highest PCE of 20.1%, with a stable current output and negligible hysteresis. Our research provides a simple and effective way for controlling the crystallization of wide-bandgap perovskite layers and hence improving the performance of wide-bandgap PSCs.