The effect of shell thickness on the performance of all-inorganic quantum dot light-emitting diodes (QLEDs) is explored by employing a series of green quantum dots (QDs) (Zn_xCd_1–xSe/ZnS core/shell QDs with different ZnS shell thicknesses) as the emitters. ZnO nanoparticles and sol–gel NiO are employed as the electron and hole transport materials, respectively. Time-resolved and steady-state photoluminescence results indicate that positive charging processes might occur for the QDs deposited on NiO, which results in emission quenching of QDs and poor device performance. The thick shell outside the core in QDs not only largely suppresses the QD emission quenching but also effectively preserves the excitons in QDs from dissociation of electron–hole pairs when they are subjected to an electric field. The peak efficiency of 4.2 cd/A and maximum luminance of 4205 cd/m² are achieved for the device based on QDs with the thickest shells (∼4.2 nm). We anticipate that these results will spur progress toward the design and realization of efficient all-inorganic QLEDs as a platform for the QD-based full-colored displays.

中文翻译：

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壳厚度对基于NiO的全无机量子点发光二极管性能的影响

通过使用一系列绿色量子点（QD）（Zn _x Cd _{1– x}具有不同ZnS壳厚度的Se / ZnS核/壳QD作为发射极。ZnO纳米粒子和溶胶-凝胶NiO分别用作电子和空穴传输材料。时间分辨和稳态光致发光结果表明，沉积在NiO上的QD可能会发生正充电过程，这会导致QD的发射猝灭和较差的器件性能。量子点中核心外部的厚壳层不仅在很大程度上抑制了量子点发射的猝灭，而且还有效地保护了量子点中的激子，使其不受电场作用下电子-空穴对的解离。峰值效率为4.2 cd / A，最大亮度为4205 cd / m ²对于基于QD且具有最厚外壳（〜4.2 nm）的设备，可实现最大输出功率。我们预计，这些结果将推动作为基于QD的全彩色显示器平台的高效全无机QLED的设计和实现取得进展。