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

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 ml of CH3NH3I and annealing at 100 degrees 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 JSC, VOC and FF.