Modified bismuth perovskite thin film morphology using greener solvent and electric-field assisted spray-coating

Abstract Eliminating lead (Pb) from the most promising perovskite active material (CH3NH3PbI3) based optoelectronic devices (OEDs) has led to exploring lead-free Organo-Metal Halide Perovskites (OMHPs). Bi-based OMHPs have captured significant attention owing to their optoelectronic properties. Bi-OMHPs are often non-conformal, hampering optical absorption and charge separation leading to the degrading device performance. To address this, conformal Bi-OMHP thin-films with improved absorption are deposited using a modified spray technique using engineered greener solvent system which greatly reduced toxicity. The developed protocol retards rapid crystallization of the material leading larger grains of ~4 µm. Further, the spray deposition under the influence of electric field (EF) facilitates fine atomization of the precursor, resulting in improved conformality with reduced pinholes. The developed spray technology combined with engineered solvent can be adaptable for eco-friendly large-scale fabrication of OEDs.