In Situ Fabrication of Lead-Free Double Perovskite/Polymer Composite Films for Optoelectronic Devices and...

Lead-free double perovskites (DP) have the potential to become a rising star in the next generation of lighting markets by addressing the toxicity and instability issues associated with traditional lead-based perovskites. However, high concentrations of hydrochloric acid (HCl) were often employed as a solvent in the preparation of most DPs, accompanied by slow crystallization at high temperatures, which not only raised the risk and cost in the preparation process, but also had a potential threat to the environment. Here, an in situ fabrication strategy was proposed to realize the crystallization of DP in the polymer at low temperature with a mild dimethyl sulfoxide (DMSO) solvent, and subsequently obtained optically well-behaved Cs₂Na_0.8Ag_0.2BiCl₆/PMMA composite films (CFs) by doping with Ag⁺, generating bright orange luminescence with a photoluminescence quantum yield (PLQY) of up to 21.52%. Moreover, the growth dynamics of Cs₂Na_0.8Ag_0.2BiCl₆/PMMA CFs was further investigated by in situ optical transformation, which was extended to other DP-based polymer CFs. Finally, these CFs exhibited excellent performance in optoelectronic devices and anticounterfeit printing, the results of which provide a new pathway to advance the development of lead-free DP materials in the optical field.