Potassium Bromide Surface Passivation on CsPbI3-xBrx Nanocrystals for Efficient and Stable Pure Red Perovskite Light-Emitting Diodes
Potassium Bromide Surface Passivation on CsPbI3-xBrx Nanocrystals for Efficient and Stable Pure Red Perovskite Light-Emitting Diodes
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CsPbI3-xBrx 纳米晶体上的溴化钾表面钝化可实现高效稳定的纯红色钙钛矿发光二极管
DOI：
10.1021/jacs.9b11719
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发表时间：
2020-02-12
影响因子：
15
通讯作者：
Yao, Hong-Bin
中科院分区：
文献类型：
--
作者：
Yang, Jun-Nan;Song, Yang;Yao, Hong-Bin
全无机卤化铅钙钛矿纳米晶（NC）由于其精确可调的带隙、高的光致发光（PL）效率和优异的色纯度而成为制备高性能发光二极管（LED）的潜在候选者。然而，纯红色（630-640 nm）全无机钙钛矿LED的性能仍然受到混合卤化物CsPbI 3-xBrx NC的电致发光（EL）的卤化物偏析诱导的不稳定性的限制。在此，我们报告了一种有效的方法来提高纯红色全无机CsPbI 3-xBrx NC基LED的电致发光稳定性，通过溴化钾钝化的NC。通过在反应体系中加入油酸钾，得到了溴化钾表面钝化的CsPbI 3-xBrx纳米碳，其光致发光量子产率（PLQY）超过90%。我们确定，大多数钾离子存在于表面上的NC与溴离子结合，从而证明溴化钾表面钝化的NC既可以提高PL稳定性，又可以抑制卤化物偏析的NC。采用KBr钝化的CsPbI 3-xBrx纳米碳作为发光层，制备了稳定的纯红色钙钛矿发光二极管，其发光波长为637 nm，最大亮度为2671 cd m（-2），最大外量子效率为3.55%，具有良好的电致发光稳定性。所提出的KBr钝化NC策略将为制造高效、稳定和可调谐的纯色钙钛矿NC LED开辟新的途径。
All-inorganic lead halide perovskite nanocrystals (NCs) are potential candidates for fabricating high-performance light-emitting diodes (LEDs) owing to their precisely tunable bandgaps, high photoluminescence (PL) efficiency, and excellent color purities. However, the performance of pure red (630-640 nm) all-inorganic perovskite LEDs is still limited by the halide segregation-induced instability of the electroluminescence (EL) of mixed halide CsPbI3-xBrx NCs. Herein, we report an effective approach to improving the EL stability of pure red all-inorganic CsPbI3-xBrx NC-based LEDs via the passivation of potassium bromide on NCs. By adding potassium oleate to the reaction system, we obtained potassium bromide surface-passivated (KBr-passivated) CsPbI3-xBrx NCs with pure red PL emission and a photoluminescence quantum yield (PLQY) exceeding 90%. We determine that most potassium ions present on the surface of NCs bind with bromide ions and thus demonstrate that potassium bromide surface passivation of NCs can both improve the PL stability and inhibit the halide segregation of NCs. Using KBr-passivated CsPbI3-xBrx NCs as an emitting layer, we fabricated stable and pure red perovskite LEDs with emission at 637 nm, showing a maximum brightness of 2671 cd m(-2), maximum external quantum efficiency of 3.55%, and good EL stability. The proposed KBr-passivated NC strategy will open a new avenue for fabricating efficient, stable, and tunable pure color perovskite NC LEDs.