Hybrid evaporation/spray-coating process for a simplified and controllable production of perovskite solar cells

Recently, hybrid processing using evaporation and spin-coating has been applied for the fabrication of perovskite silicon tandem solar cells with record power conversion efficiencies (PCEs) of 25.2%. To achieve large area, high-throughput production of solar cells, spray-coating, a well-known scalable method used in the industry, has advantages over spin-coating. Therefore, we apply a hybrid method using the evaporation of PbI2 and spraying of methylammonium iodide (MAI) for the fabrication of perovskite solar cells. This article presents a systematic study of sprayed MAI amount and processing parameters on the performance of solar cells. We find clear correlations between the processing parameters of the sprayed MAI, the crystallinity of CH3NH3PbI3 and the PCE of the resulting PSCs. High crystallinity and morphology of the CH3NH3PbI3 film is achieved using a slow nozzle speed of 30 mm·s−1. An average PCE of 11.6% ± 3.1% (maximum PCE of 14.3%, stabilized PCE of 10%) was achieved with a normalized MAI amount of 3.4, which represent the flow rate of 0.17 ml·min−1, nozzle speed of 30 mm·s−1, MAI concentration of 9 mg·mL−1, and one single spray pass. Moreover, we successfully show a proof-of-concept of this method for the deposition of homogenous perovskite layers on pyramidal textured silicon.