Material nucleation/growth competition tuning towards highly reproducible planar perovskite solar cells with efficiency exceeding 20%

Abstract

Since there are still challenges in fabricating high-quality large-area perovskite films, perovskite solar cells have limitations for industrial application. Here, we develop a material nucleation/growth competition theory to guide us to tune the nucleation and grain growth process of perovskite. Subsequently, we introduce a gas-flow-induced gas pump approach for the large-area deposition of dense, uniform and full-coverage perovskite films, and this process is simple with high manufacturing efficiency and a wide process window. This enabled us to fabricate uniform perovskite films on substrates with the largest area of up to 144 cm². Normal planar perovskite solar cells were fabricated at pressures of 100 Pa, 500 Pa and 1500 Pa, achieving average efficiencies of 19.25 ± 0.50%, 19.17 ± 0.46% and 18.98 ± 0.51% respectively for 0.1 cm² devices (84 devices in total) with ultrahigh reproducibility. A high fill factor of up to 80% was obtained at different pressures. A champion cell with an efficiency of 20.44% was obtained which is one of the highest efficiencies for normal planar perovskite solar cells. Furthermore, we achieved an efficiency of 17.03%, the highest efficiency for normal perovskite solar cells with the device area exceeding 1 cm² and an average efficiency of 15.63 ± 0.80% with an area of 1.1275 cm² (for 30 devices).