Lyu Bingbing, Hu Junxia, Chen Yani, Ma Zhiwei
School of Physics, Harbin Institute of Technology, Harbin 150001, China.
School of Information Engineering, Xinyang Agriculture and Forestry University, Xinyang 464000, China.
Micromachines (Basel). 2022 Aug 14;13(8):1315. doi: 10.3390/mi13081315.
The band level landscape in quantum dots is of great significance toward achieving stable and efficient electroluminescent devices. A series of quantum dots with specific emission and band structure of the intermediate layer is designed, including rich CdS (R-CdS), thick ZnSe (T-ZnSe), thin ZnSe (t-ZnSe) and ZnCdS (R-ZnCdS) intermediate alloy shell layers. These quantum dots in QLEDs show superior performance, including maximum current efficiency, external quantum efficiencies and a T lifetime (at 1000 cd/m) of 47.2 cd/A, 11.2% and 504 h for R-CdS; 61.6 cd/A, 14.7% and 612 h for t-ZnSe; 70.5 cd/A, 16.8% and 924 h for T-ZnSe; and 82.0 cd/A, 19.6% and 1104 h for R-ZnCdS. Among them, the quantum dots with the ZnCdS interlayer exhibit deep electron confinement and shallow hole confinement capabilities, which facilitate the efficient injection and radiative recombination of carriers into the emitting layer. Furthermore, the optimal devices show a superior T lifetime of more than 1000 h. The proposed novel methodology of quantum dot band engineering is expected to start a new way for further enhancing QLED exploration.
量子点中的能带水平态势对于实现稳定高效的电致发光器件具有重要意义。设计了一系列具有特定发射和中间层能带结构的量子点，包括富硫化镉（R-CdS）、厚硒化锌（T-ZnSe）、薄硒化锌（t-ZnSe）和锌镉硫化物（R-ZnCdS）中间合金壳层。这些用于量子点发光二极管（QLED）的量子点表现出优异的性能，对于R-CdS，最大电流效率、外量子效率以及在1000 cd/m²时的T寿命分别为47.2 cd/A、11.2%和504小时；对于t-ZnSe，分别为61.6 cd/A、14.7%和612小时；对于T-ZnSe，分别为70.5 cd/A、16.8%和924小时；对于R-ZnCdS，分别为82.0 cd/A、19.6%和1104小时。其中，具有锌镉硫化物中间层的量子点表现出深电子限制和浅空穴限制能力，这有利于载流子有效地注入发光层并进行辐射复合。此外，优化后的器件表现出超过1000小时的优异T寿命。所提出的量子点能带工程新方法有望为进一步加强量子点发光二极管的探索开辟一条新途径。
