Polymer additive engineering of K2CuBr3 nanocrystalline films to achieve efficient and stable deep-blue emission

Recently, non-toxic alternatives to lead-halide perovskites have been greatly sought after in optoelectronics applications. Deep-blue luminescent material is mainly required for fabricating white light source and expanding the color gamut of full-color displays. However, the synthesis of high-performance lead-free perovskite films with efficient blue emission is still a critical challenge currently, limiting their further practical applications. Here, a novel strategy is reported to prepare non-toxic and deep-blue-emitting K2CuBr3 nanocrystalline films by introducing polymer poly(methyl methacrylate) (PMMA) additives into the anti-solvent. It is found that the PMMA additives could effectively reduce the grain size and improve the crystallinity of K2CuBr3 films, resulting in an enhanced radiative recombination by defect passivation and confinement of excitons in the nanograins. As a result, the PMMA-treated K2CuBr3 films achieve a bright deep-blue light with color coordinates at (0.155, 0.042), and the photoluminescence quantum yield obtained is about 3.3 times that of the pristine sample. Moreover, the treated K2CuBr3 films exhibit a substantially enhanced stability under harsh environmental conditions, maintaining >70% of their initial performances in high humidity environment (50%-70% humidity, 190 h) or under uninterrupted ultraviolet light radiation (254 nm, 3.4 mW cm(-2), 150 h). These findings pave a promising strategy for achieving efficient and stable deep-blue metal halide films, showing their potential applications in optoelectronic devices.

Automated summary

This study reports a novel strategy to prepare non-toxic and deep-blue-emitting K2CuBr3 nanocrystalline films by introducing PMMA additives into the anti-solvent. The PMMA additives improve the crystallinity of the films, enhance the photoluminescence quantum yield, and enhance the stability of the films under harsh environmental conditions.