基于 In$_{{\bf 1}-x}$Ga$_{x}$P 梯度合金核无镉量子点的制备及 LED 应用

低毒性磷化铟量子点(indium phosphide quantum dot, InP QD)作为最有可能取代有毒重金属镉基量子点的材料, 已经在下一代商业显示和照明领域中显示出巨大潜力. 然而, 合成具有高荧光量子产率(photoluminescence quantum yield, PL QY)的InP QD 仍然具有挑战性. 因此, 提出了以乙酰丙酮镓作为镓源, 在高温下通过乙酰丙酮基对表面配体的活化作用, 生成具有梯度合金核的 In$_{1-x}$Ga$_{x}$P/ZnSe/ZnS 量子点, 有效解决了原有的 InP 与 ZnSe 之间晶格失配的问题; 同时减少核壳界面缺陷, 使量子点的荧光量子产率高达 82%, 所制备量子点发光二极管(quantum dot light-emitting diode, QLED)的外量子效率(external quantum efficiency, EQE)达到 3.1%. 相比传统的 InP/ZnSe/ZnS 结构量子点, In$_{1-x}$Ga$_{x}$P/ZnSe/ZnS 量子点荧光量子产率提高了 25%, 器件的外量子效率提高了近一倍. 该方案为解决 InP 量子点荧光量子产率低、发光器件性能差等问题提供了新的思路.

Synthesis of alloyed In$_{{\bf 1-}x}$Ga$_{x}$P quantum dots and their application to LEDs

As alternatives to quantum dots based on cadmium, a toxic heavy metal, low-toxicity indium phosphide quantum dots (InP QDs) have shown excellent potential for application in next-generation commercial displays and illumination devices. However, the synthesis of InP QDs with high photoluminescence quantum yields (PL QYs) remains challenging. Therefore, the use of gallium acetylacetonate is proposed as a gallium source to activate surface ligands via acetylacetone at a high temperature to form In$_{1-x}$Ga$_x$P/ZnSe/ZnS with a gradient alloyed core, effectively solving the lattice mismatch between InP and ZnSe. Meanwhile, the gradient alloyed core can reduce the defects among interfaces, such that the PL QY of quantum dots is up to 82% and the external quantum efficiency of the prepared quantum dot light-emitting diode (QLED) reaches 3.1%. Compared to QDs with the traditional InP/ZnSe/ZnS structure, the In$_{1-x}$Ga$_x$P/ZnSe/ZnS QDs yield a PL QY enhancement of 25%, and the external quantum efficiency of the device is nearly doubled. This scheme provides a new method for solving the problems of lowPL QY of InP QDs and poor performance of light-emitting devices.