Perovskite light‐emitting diodes (PeLEDs) have attracted great research interests considering their excellent luminescent properties and solution processability. Despite rapid advances of green‐, red‐, and near‐infrared‐emitting PeLEDs, blue‐PeLEDs, as an essential part for full‐color display and solid‐state lighting, still remain challenging due to their low efficiency and spectral instability. Here, reported are spectrally stable blue‐PeLEDs biased by an alternating voltage. First, 2‐phenoxyethylamine‐passivated CsPbBr_xCl_3−x is obtained as a blue emitter with a record photoluminescence quantum yield of 88%. Subsequently, constructed and optimized are pure blue‐emitting PeLEDs exhibiting electroluminescence (EL) at 468 nm with a high external quantum efficiency of 0.71%. Furthermore, driven are the devices by square‐wave alternating voltage and stabilized are the EL spectra for 12 h by suppressing the detrimental halide migration during operation. It is believed that this work provides an alternative way for the spectrally stable mixed halide blue PeLEDs.

中文翻译：

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方波交流电压增强的光谱稳定的超纯蓝色钙钛矿发光二极管

钙钛矿发光二极管（PeLEDs）具有出色的发光性能和溶液加工性能，因此引起了广泛的研究兴趣。尽管发出绿色，红色和近红外光的PeLED迅速发展，但作为全色显示和固态照明必不可少的部分，蓝色PeLED仍然因其低效率和光谱不稳定而仍然具有挑战性。在此，报告了由交流电压偏置的光谱稳定的蓝色PeLED。首先是2-苯氧基乙胺钝化的CsPbBr _x Cl _{3− x}获得的蓝光发射体具有创纪录的88％的光致发光量子产率。随后，构建并优化了纯蓝光发射的PeLED，它们在468 nm处显示电致发光（EL），具有0.71％的高外部量子效率。此外，通过方波交流电压驱动设备，并通过抑制操作过程中有害的卤化物迁移，稳定了12 h的EL光谱。相信这项工作为光谱稳定的混合卤化物蓝PeLED提供了另一种方法。