Chrzanowski Maciej, Zatryb Grzegorz, Sitarek Piotr, Podhorodecki Artur
Department of Experimental Physics, Wroclaw University of Science and Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland.
ACS Appl Mater Interfaces. 2021 May 5;13(17):20305-20312. doi: 10.1021/acsami.1c01898. Epub 2021 Apr 23.
We demonstrate the effect of air exposure on optical and electrical properties of ZnMgO nanoparticles (NPs) typically exploited as an electron transport layer in Cd-based quantum-dot light-emitting diodes (QLEDs). We analyze the roles of air components in modifying the electrical properties of ZnMgO NPs, which reveals that HO enables the reduction of hole leakage while O alters the character of charge transport due to its ability to trap electrons. As a result, the charge balance in the QDs layer is improved, which is confirmed by voltage-dependent measurements of photoluminescence quantum yield. The maximum external quantum efficiency is improved over 2-fold and reaches the value of 9.5% at a luminance of 10 cd/m. In addition, we investigate the problem of electron leakage into the hole transport layer and show that trap-mediated electron transport in the ZnMgO layer caused by adsorbed O ensures a higher leakage threshold. This work also provides an insight into the possible disadvantages of device contact with air as well as problems and challenges that might occur during open-air fabrication of QLEDs.
我们展示了空气暴露对典型用于镉基量子点发光二极管（QLED）中作为电子传输层的ZnMgO纳米颗粒（NPs）的光学和电学性质的影响。我们分析了空气成分在改变ZnMgO NPs电学性质中的作用，结果表明，HO能够减少空穴泄漏，而O因其捕获电子的能力改变了电荷传输特性。结果，量子点层中的电荷平衡得到改善，这通过光致发光量子产率的电压依赖性测量得到证实。最大外量子效率提高了两倍多，在亮度为10 cd/m时达到9.5%的值。此外，我们研究了电子泄漏到空穴传输层的问题，并表明由吸附的O引起的ZnMgO层中的陷阱介导电子传输确保了更高的泄漏阈值。这项工作还深入了解了器件与空气接触可能存在的缺点以及在QLED的露天制造过程中可能出现的问题和挑战。
