Unravelling Alkali-Metal-Assisted Domain Distribution of Quasi-2D Perovskites for Cascade Energy Transfer toward Efficient Blue Light-Emitting Diodes,Advanced Science

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Unravelling Alkali-Metal-Assisted Domain Distribution of Quasi-2D Perovskites for Cascade Energy Transfer toward Efficient Blue Light-Emitting Diodes
Advanced Science ( IF 14.3 ) Pub Date : 2022-05-13 , DOI: 10.1002/advs.202200393
Wanqing Cai _{1,

2} , Muhammad Umair Ali _{1,

2} , Ping Liu _{1,

2} , Miao He _{1,

2} , Cong Zhao _{1,

2} , Ziming Chen ₃ , Yue Zang ₃ , Man-Chung Tang _{1,

2} , Hong Meng ₄ , Hongyan Fu _{1,

2} , Guodan Wei _{1,

2} , Hin-Lap Yip _{3,

5,

6}

Affiliation

Solution processable quasi-2D (Q-2D) perovskite materials are emerging as a promising candidate for blue light source in full-color display applications due to their good color saturation property, high brightness, and spectral tunability. Herein, an efficient energy cascade channel is developed by introducing sodium bromide (NaBr) in phenyl-butylammonium (PBA)-containing mixed-halide Q-2D perovskites for a blue perovskite light-emitting diode (PeLED). The incorporation of alkali metal contributes to the nucleation and growth of Q-2D perovskites into graded distribution of domains with different layer number <n>. The study of excitation dynamics by transient absorption (TA) spectroscopy confirms that NaBr induces more Q-2D perovskite phases with small n number, providing a graded energy cascade pathway to facilitate more efficient energy transfer processes. In addition, the nonradiative recombination within the Q-2D perovskites is significantly suppressed upon Na⁺ incorporation, as validated by the trap density estimation. Consequently, the optimized blue PeLEDs manifest a peak external quantum efficiency (EQE) of 7.0% emitting at 486 nm with a maximum luminance of 1699 cd m⁻². It is anticipated that these findings will improve the understanding of alkali-metal-assisted optimization of Q-2D perovskites and pave the way toward high-performance blue PeLEDs.

中文翻译：

揭示准二维钙钛矿的碱金属辅助域分布，用于向高效蓝光发光二极管的级联能量转移

可溶液加工的准二维（Q-2D）钙钛矿材料由于其良好的色彩饱和度、高亮度和光谱可调性，正在成为全彩显示应用中蓝色光源的有希望的候选材料。在此，通过在含有苯基丁基铵 (PBA) 的混合卤化物 Q-2D 钙钛矿中引入溴化钠 (NaBr) 开发了一种高效的能量级联通道，用于蓝色钙钛矿发光二极管 (PeLED)。碱金属的掺入有助于 Q-2D 钙钛矿的成核和生长成不同层数 < n > 的畴的分级分布。通过瞬态吸收 (TA) 光谱对激发动力学的研究证实，NaBr 可诱导更多的 Q-2D 钙钛矿相，且n数量，提供分级的能量级联路径，以促进更有效的能量转移过程。此外，如陷阱密度估计所证实的， Q-2D 钙钛矿内的非辐射复合在 Na ^{+掺入时受到显着抑制。}因此，优化的蓝色 PeLED 表现出 7.0% 的峰值外部量子效率 ( EQE )，发射波长为 486 nm，最大亮度为 1699 cd m ^-2。预计这些发现将提高对碱金属辅助优化 Q-2D 钙钛矿的理解，并为高性能蓝色 PeLED 铺平道路。

更新日期：2022-05-13

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