Postannealing-Free Dry–Wet Hybrid Deposition of CsPbBr₃ Thin Film via Aqueous Spray-Coating

We propose evaporation–spray hybrid (E–S hybrid) process for fabricating high-quality CsPbBr3 perovskite films, addressing challenges associated with conventional fabrication methods. The E–S hybrid process employs vacuum evaporation to produce a uniform PbBr2 underlayer with small crystal domains, enhancing the subsequent reaction with a spray-coated CsBr aqueous solution. This approach yields CsPbBr3 films free of pinholes, exhibiting polycrystalline packing with crystal sizes of approximately 500 nm, without the need for toxic solvents or postannealing. Structural and compositional evaluations confirm the successful formation of orthorhombic CsPbBr3 films. Optical characterizations demonstrate sharp excitonic absorption signals and excellent photoluminescence features. Furthermore, a microcavity device fabricated using the E–S hybrid method successfully exhibits a polariton mode with a high-quality factor, highlighting the potential of this method for polaritonic device applications. The E–S hybrid method offers a promising and environmentally friendly approach for the preparation of high-quality all-inorganic lead-halide perovskite films suitable for optoelectronic and polaritonic applications.