Efficient and Stable All-Inorganic CsPbIBr2 Perovskite Solar Cells Enabled by Dynamic Vacuum-Assisted Low-Temperature Engineering

Among all-inorganic perovskite photoactive materials, CsPbIBr2 demonstrates the most balanced trade-off between optical bandgap and phase stability. However, the poor quality and high-temperature engineering of CsPbIBr2 film hinder the further optimization of derived perovskite solar cells (PSCs). Herein, a simple dynamic vacuum-assisted low-temperature engineering (merely 140 degrees C) is proposed to prepare high-quality CsPbIBr2 film (VALT-CsPbIBr2 film). Compared to HT-CsPbIBr2 film processed via conventionally high temperature (280 degrees C), VALT-CsPbIBr2 film presents higher crystallinity and more full coverage consisting of larger grains and fewer grain boundaries, which results in intensified light-harvesting capability, reduced defects, and extended charge carrier lifetime. Benefiting from those improved merits, VALT-CsPbIBr2 PSCs show lower trap-state densities, more proficient charge dynamics, and larger built-in potential than HT-CsPbIBr2 PSCs. Consequently, VALT-CsPbIBr2 PSCs deliver a higher efficiency of 11.01% accompanied by a large open-circuit voltage of 1.289 V and a remarkable fill factor of 75.31%, being highly impressive among those reported CsPbIBr2 PSCs. By contrast, the efficiency of HT-CsPbIBr2 PSCs is only 9.00%. Moreover, VALT-CsPbIBr2 PSCs present stronger endurance against heat and moisture than HT-CsPbIBr2 PSCs. Herein, a feasible avenue to fabricate efficient yet stable all-inorganic PSCs via low-temperature engineering is provided.

Automated summary

The VALT-CsPbIBr2 film prepared through dynamic vacuum-assisted low-temperature engineering shows superior performance in optical properties and microstructure, leading to increased efficiency and stability of perovskite solar cells.