One-step <italic>in</italic>-<italic>situ</italic> Synthesis of Cs₂NaInCl₆@PVDF Films: Doping Regulation and Optical Properties

Abstract Lead-free halide double perovskites (DPs) are emerging as one of the most promising alternatives to lead halide perovskites due to their non-toxicity high efficiency stability and excellent optoelectronic properties.These attributes make them highly attractive for applications in lighting and display technologies.However the cur rent fabrication methods for double perovskite luminescent films are often complex and associated with significant safety concerns which severely hinder their commercialization.In this study we present a one-step in-situ synthesis of Cs 2 NaInCl 6 @PVDF (polyvinylidene fluoride) films.By doping the Cs 2 NaInCl 6 host material with Sb 3+ we success fully overcame the parity-forbidden transitions enabling bright blue luminescence from self-trapped excitons (STEs).The resulting emission peak is centered at 450 nm with a full width at half maximum (FWHM) of approxi mately 80 nm and a maximum photoluminescence quantum yield (PLQY) of 71.0%.The film demonstrates remarkable