All‐inorganic CsPbI3 perovskite semiconductor is attractive for deep‐red light‐emitting diodes (LEDs) because of its high photoluminescence, good thermal stability, excellent charge transport, and solution processability. However, the metastable phase of optically active CsPbI3 hinders the fabrication of efficient and bright deep‐red LEDs. Herein, a multifunctional ionic ligand regulation strategy using (2‐hydroxy‐5‐methylphenyl) triphenyl‐phosphonium iodide and 3‐(N, N‐dimethyloctylammonio) propanesulfonate is reported to regulate the optically active CsPbI3 crystallization and thus obtain high‐quality γ‐CsPbI3 thin films. The high crystallinity and preferential orientation of γ‐CsPbI3 arise from the strong bonding between the ionic ligands and ionic lead halide clusters. The obtained γ‐CsPbI3 thin films also possess suppressed defect densities, high luminescence, and high stability. Using this high‐quality thin film, an efficient and bright deep‐red LED with a peak external quantum efficiency of 13.34% and a maximum luminance of 2110 cd m−2 is successfully fabricated. The operational lifetime of the fabricated LED (time to half of the initial brightness, T50) reaches up to 40 min under a high current density of 50 mA cm−2 (corresponding to the initial brightness of 200 cd m−2).

中文翻译：

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多功能离子配体调控的高质量 γ-CsPbI3 薄膜，用于高效、明亮的深红色发光二极管

全无机CsPbI3钙钛矿半导体因其高光致发光、良好的热稳定性、优异的电荷传输和溶液加工性能而对深红色发光二极管（LED）具有吸引力。然而，光学活性 CsPbI 的亚稳态相3阻碍了高效、明亮的深红色 LED 的制造。在此，报道了使用（2-羟基-5-甲基苯基）三苯基碘化鏻和3-（N，N-二甲基辛基铵）丙烷磺酸盐的多功能离子配体调节策略来调节光学活性CsPbI3结晶，从而获得高质量的γ-CsPbI3薄膜。 γ-CsPbI的高结晶度和择优取向3由离子配体和离子卤化铅簇之间的强键合产生。所得γ-CsPbI3薄膜还具有抑制缺陷密度、高发光性和高稳定性。使用这种高质量薄膜，可制成高效、明亮的深红光 LED，峰值外量子效率为 13.34%，最大亮度为 2110 cd m−2就制作成功了。所制造 LED 的使用寿命（达到初始亮度一半的时间，时间50）在50 mA cm的高电流密度下达到长达40分钟−2（对应初始亮度200cd·m−2）。