Enhanced Coverage of All-Inorganic Perovskite CsPbBr₃ through Sequential Deposition for Green Light-Emitting Diodes

Film morphology has a major influence on the performance of halide perovskite semiconductors, where poor coverage and pinholes are generally detrimental and result in undesirable current leakage. All-inorganic cesium lead bromide (CsPbBr₃) has an advantage of improved stability especially under device operation, but the low solubility of the ionic precursor CsBr limits the coverage of the solution-processed film. To tackle this, a sequential deposition technique is proposed whereby PbBr₂ is first deposited on a planar substrate prior to exposure to a CsBr solution to initiate conversion to the desired CsPbBr₃ phase. This approach essentially nullifies the solubility problem of CsBr and the final perovskite film coverage now chiefly depends on the initial PbBr₂ concentration and the duration of exposure to the CsBr solution. With over 90 % film coverage achieved, a proof of concept perovskite light-emitting diode (PeLED) with green emission at 527 nm has also been achieved, thereby demonstrating the feasibility of this methodology for future device fabrication.