High-Voltage-Efficiency Inorganic Perovskite Solar Cells in a Wide Solution-Processing Window

Inorganic halide perovskites exhibit significant photovoltaic performance due to their structural stability and high open-circuit voltage (V-oc). Herein, a general strategy of solution engineering has been implemented to enable a wide solution-processing window for high V-oc (similar to 1.3 V) and power conversion efficiency (PCE, similar to 12.5%). We introduce a nontoxic solvent of dimethyl sulfoxide (DMSO) and an assisted heating process in the fabrication of CsPbI2Br (CPI2) to control the improved crystallization. A wide solution-processing window including a wide range of solvent components and solute concentrations has been realized. The CPI2-based inorganic perovskite solar cells (IPSCs) exhibit a high PCE up to 12.52%. More importantly, these devices demonstrate a remarkable V-oc of 1.315 V. The performance has possessed such a region with high V-oc and PCE in all Cs-based IPSCs, unveiling wide solution-processing windows with enhanced solution processability facilitating potential industrial application especially for tandem solar cells.