Pure-red emission light-emitting diodes (LEDs) are highly desirable for display and lighting applications. Here, we present a synergistic approach to fabricate pure-red emission LEDs based on quantum-confined CsPbI nanocrystals (NCs). By introducing ZnI acting as a co-precursor and passivating agent into the synthesis, and applying a gradient post-synthesis purification method allowing us to obtain size-selected fractions with precisely adjusted emission colors, we obtained uniform and small (about 6 nm), quantum-confined CsPbI NCs exhibiting high stability in ambient conditions and a superior photoluminescence quantum yield of up to 88%. These NCs exhibited the tendency to undergo oriented attachment, resulting in self-assembled superstructures with a pure-red emission at 629 nm. Importantly, partial recrystallization into fused superstructures led to removal of the insulating ligand barriers between NCs. LEDs based on the CsPbI NCs showed pure-red electroluminescence at 633 nm, with an external quantum efficiency of 14.7% and a luminance of over 1000 cd/m. Our study reveals the mechanism behind the oriented attachment and assembly of small, quantum-confined CsPbI NCs, and contributes to the development of pure-red electroluminescent LEDs.

中文翻译：

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梯度纯化法获得的量子限域CsPbI3钙钛矿纳米晶的纯红色电致发光

纯红光发光二极管 (LED) 非常适合显示和照明应用。在这里，我们提出了一种基于量子限制的 CsPbI 纳米晶体 (NC) 制造纯红色发射 LED 的协同方法。通过将 ZnI 作为共前体和钝化剂引入合成中，并应用梯度合成后纯化方法，使我们能够获得具有精确调整的发射颜色的尺寸选择的级分，我们获得了均匀且小的（约 6 nm），量子限制的 CsPbI NC 在环境条件下表现出高稳定性，并且光致发光量子产率高达 88%。这些 NC 表现出进行定向附着的倾向，从而产生在 629 nm 处发出纯红色发射的自组装超结构。重要的是，部分重结晶成熔融超结构导致NC之间绝缘配体势垒的去除。基于CsPbI NCs的LED在633 nm处显示出纯红色电致发光，外量子效率为14.7%，亮度超过1000 cd/m2。我们的研究揭示了小型量子限制 CsPbI NC 定向附着和组装背后的机制，并有助于纯红色电致发光 LED 的开发。