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

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 cm(2). 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 cm(2) 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 cm(2) (for 30 devices).