Decreasing perovskite nanocrystal size increases radiative recombination due to the quantum confinement effect, but also increases the Auger recombination rate which leads to carrier imbalance in the emitting layers of electroluminescent devices. Here, we overcome this trade‐off by increasing the exciton effective mass without affecting the size, which is realized through the trace Cd2+ doping of formamidinium lead bromide perovskite nanocrystals. We observe an ~2.7 times increase in the exciton binding energy benefiting from a slight distortion of the [BX6]4− octahedra caused by doping in the case of that the Auger recombination rate is almost unchanged. As a result, bright color‐saturated green emitting perovskite nanocrystals with a photoluminescence quantum yield of 96% are obtained. The light‐emitting devices based on those nanocrystals reached a high external quantum efficiency (EQE) of 29.4% corresponding to a current efficiency of 123 cd A‐1, and showed dramatically improved device lifetime, with a narrow bandwidth of 22 nm and Commission Internationale de I’Eclairage coordinates of (0.20, 0.76) for color‐saturated green emission for the electroluminescence peak centered at 534 nm, thus being fully compliant with the latest standard for wide color gamut displays.

中文翻译：

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通过微量镉 (II) 掺杂微调溴化铅钙钛矿纳米晶体的晶体结构，实现高效、色彩饱和的绿色 LED

由于量子限制效应，减小钙钛矿纳米晶体尺寸会增加辐射复合，但也会增加俄歇复合率，从而导致电致发光器件的发射层中的载流子不平衡。在这里，我们通过在不影响尺寸的情况下增加激子有效质量来克服这种权衡，这是通过甲脒溴化铅钙钛矿纳米晶体的痕量Cd2+掺杂实现的。我们观察到，在俄歇复合率几乎不变的情况下，由于掺杂引起的 [BX6]4− 八面体的轻微变形，激子结合能增加了约 2.7 倍。结果，获得了光致发光量子产率为96%的明亮颜色饱和绿光发射钙钛矿纳米晶。基于这些纳米晶体的发光器件达到了 29.4% 的高外量子效率 (EQE)，相当于 123 cd A-1 的电流效率，并显示出显着提高的器件寿命，具有 22 nm 的窄带宽和国际委员会de I'Eclairage 坐标为 (0.20, 0.76)，电致发光峰以 534 nm 为中心的颜色饱和绿色发射，因此完全符合宽色域显示器的最新标准。