Key Lab of Physics and Technology for Advanced Batteries (Ministry of Education), College of Physics , Jilin University , 2699 Qianjin Street , Changchun 130012 , China.
Institute of Applied Physics and Materials Engineering , University of Macau , Avenida da Universidade , Taipa 999078 , Macau SAR , China.
ACS Appl Mater Interfaces. 2018 May 2;10(17):14894-14900. doi: 10.1021/acsami.8b01814. Epub 2018 Apr 19.
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 CdSe/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/m 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.
通过使用一系列绿色量子点（QDs）（具有不同 ZnS 壳厚度的 ZnCdSe/ZnS 核/壳 QDs）作为发射器，研究了壳厚度对全无机量子点发光二极管（QLED）性能的影响。氧化锌纳米粒子和溶胶-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，可能会发生在 NiO 上沉积的 QDs 的正充电过程，这导致 QDs 的发射猝灭和器件性能不佳。在 QDs 中，核外的厚壳不仅极大地抑制了 QD 的发射猝灭，而且当它们受到电场时，还有效地保护了 QD 中的激子免于电子-空穴对的离解。基于具有最厚壳（约 4.2nm）的 QDs 的器件实现了 4.2cd/A 的峰值效率和 4205cd/m 的最大亮度。我们预计这些结果将推动高效全无机 QLED 的设计和实现，作为基于 QD 的全彩色显示器的平台。
