Water as the Only Solvent for CsPbCl₃ and NIR‐Emitting CsPbCl₃:Yb³⁺ Films by Antisolvent‐Enhanced Crystallization in Aerosol‐Assisted Chemical Vapor Deposition

Abstract CsPbX₃ (X = Cl, Br, I) perovskites have emerged as promising materials for optoelectronic applications. However, thin film synthesis has essential issues such as chemical stability, toxicity, and processability. In this work, a green synthesis approach using water as the only solvent to deposit CsPbCl₃ and CsPbCl₃:Yb³⁺ films by aerosol assisted chemical vapor deposition technique under ambient atmospheric conditions, is proposed. X‐ray diffraction pattern and X‐ray photoelectron spectroscopy analysis confirm the phase purity and negligible degradation by using water during deposition. Moreover, CsPb₂Cl₅ secondary phase is detected as a substitution and anchoring doped mechanism response for doped materials. Additionally, green antisolvents (alcohols and propan‐2‐one) are used to assist the crystallization process; all the green antisolvents result in an increased substrate coverage, highlighting those with high boiling points and low heat of combustion that promote heterogeneous nucleation. As‐deposited films show a photoluminescent excitonic emission peak around 418 nm and an additional peak at 984 nm emission band associated with the Yb³⁺ infrared 2F^5/2 to 2F^7/2 transitions for doped materials. Near infra‐red photoluminescence emission is notably improved upon antisolvent assistance up to a threefold increase for ethanol, reaching a photoluminescence quantum yield of 33.94% at low Yb³⁺ concentration.