Preparation of metal halide perovskite solar cells through a liquid droplet assisted method

Abstract

Solution-processed organometal trihalide-based perovskites have attracted attention in the field of solar energy due to their high absorption and low temperature fabrication. We demonstrated the droplet-assisted two-step process of spin coating lead iodide (PbI₂) followed by spray coating methylammonium iodide (CH₃NH₃I) to prepare a continuous lead iodide perovskite film. A simple airbrush gun was used to control the volume of CH₃NH₃I, in order to attain a uniform, stoichiometric and continuous perovskite film. An insufficient or excess volume of CH₃NH₃I gives poor crystallinity and morphology, which gradually reduces the device performance. A power conversion efficiency (PCE) of 11.66% was achieved for 100 nm of PbI₂ followed by 300 μl of CH₃NH₃I and annealing at 100 °C for 120 min. To address the reproducibility of the device performance, 50 devices were fabricated for statistical analysis and 80% of the devices showed the average PCE of 10–11% with reproducible J_SC, V_OC and FF.