Bright and efficient blue emission is key to further development of metal halide perovskite light-emitting diodes. Although modifying bromide/chloride composition is straightforward to achieve blue emission, practical implementation of this strategy has been challenging due to poor colour stability and severe photoluminescence quenching. Both detrimental effects become increasingly prominent in perovskites with the high chloride content needed to produce blue emission. Here, we solve these critical challenges in mixed halide perovskites and demonstrate spectrally stable blue perovskite light-emitting diodes over a wide range of emission wavelengths from 490 to 451 nanometres. The emission colour is directly tuned by modifying the halide composition. Particularly, our blue and deep-blue light-emitting diodes based on three-dimensional perovskites show high EQE values of 11.0% and 5.5% with emission peaks at 477 and 467 nm, respectively. These achievements are enabled by a vapour-assisted crystallization technique, which largely mitigates local compositional heterogeneity and ion migration.

明亮高效的蓝光发射是进一步发展金属卤化物钙钛矿发光二极管的关键。尽管修改溴化物/氯化物的组成很容易实现蓝色发射，但是由于不良的颜色稳定性和严重的光致发光猝灭，该策略的实际实施一直具有挑战性。钙钛矿中产生蓝色发射所需的高氯化物含量，两种有害作用都日益突出。在这里，我们解决了混合卤化物钙钛矿中的这些关键挑战，并演示了在490至451纳米的宽发射波长范围内光谱稳定的蓝色钙钛矿发光二极管。通过改变卤化物组成直接调节发射颜色。尤其，我们基于三维钙钛矿的蓝色和深蓝色发光二极管显示出较高的EQE值，分别为11.0％和5.5％，发射峰分别位于477和467 nm。这些成就是通过蒸气辅助结晶技术实现的，该技术大大减轻了局部成分的异质性和离子迁移。