Highly stable blue perovskite light-emitting electrochemical cell realized by synergistic optimization of polyethylene oxide and lithium salts
Résumé
High-performance blue light-emitting devices are essential for solid-state lighting and full-color displays. Among them, metal halide perovskite semiconductors show great potential in solution-processed blue light-emitting devices. The mixed halide Cl/Br perovskite provides one of the easiest ways to achieve emission in the blue region. However, its inherent ion movement and separation lead to halide segregation under light and voltage driving. Here, polyelectrolytes and a salt additive are leveraged to suppress the halide segregation in the single-layer CsPbBr3-xClx perovskite light-emitting electrochemical cells (LECs). The ions from the salt addition are transported by the electrolyte, improving charge injection and maintaining the intrinsic perovskite lattice of luminescence, resulting in pure and sustained blue emission. These devices achieve stable blue electroluminescence at 490 nm with a maximum brightness of 242 cd m$^{−2}$. These results indicate polymer and salt additive inclusion increases photoluminescence efficiency, suppresses halide segregation, and induces thin-film smoothness and uniformity.
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