Xu Bo, Yuan Shichen, Wang Linqin, Li Xiansheng, Hu Zhuang, Zeng Haibo
MIIT Key Laboratory of Advanced Display Materials and Devices, Jiangsu Province Engineering Research Center of Quantum Dot Display, School of Materials Science and Engineering, Institute of Optoelectronics & Nanomaterials, Nanjing University of Science and Technology, Nanjing, Jiangsu 210094, China.
Center of Artificial Photosynthesis for Solar Fuels and Department of Chemistry, School of Science, Westlake University, Hangzhou 310024, P. R. China.
ACS Nano. 2025 Jan 28;19(3):3694-3704. doi: 10.1021/acsnano.4c14276. Epub 2025 Jan 10.
Room temperature (RT) synthesized mixed bromine and chlorine CsPbBrCl perovskite quantum dots (Pe-QDs) offer notable advantages for blue quantum dot light-emitting diodes (QLEDs), such as cost-effective processing and narrow luminescence peaks. However, the efficiency of blue QLEDs using these RT-synthesized QDs has been limited by inferior crystallinity and deep defect presence. In this study, we demonstrate a precise approach to constructing high-quality gradient core-shell (CS) structures of CsPbBrCl QD through anion exchange. Characterization shows that these CS-QDs exhibit a type-I band alignment with a high bromine concentration in the core and a high chlorine concentration in the shell. This unique configuration results in a larger exciton binding energy and reduced defect density, leading to enhanced exciton radiative recombination. Consequently, QLEDs using CS-QDs achieve an external quantum efficiency (EQE) of 16.28%, a maximum luminance of 8423.35 cd/m, and improved operational stability, surpassing the 12.80% EQE of reference QLEDs made with homogeneous structured QDs (HS-QDs). These findings present a strategy for developing high-quality RT-synthesized blue CS-QDs, marking a significant advancement in the field of efficient pure-blue QLEDs.
室温（RT）合成的混合溴和氯的CsPbBrCl钙钛矿量子点（Pe-QDs）为蓝色量子点发光二极管（QLEDs）提供了显著优势，如具有成本效益的加工工艺和窄发光峰。然而，使用这些室温合成量子点的蓝色QLEDs的效率一直受到结晶度差和存在深缺陷的限制。在本研究中，我们展示了一种通过阴离子交换构建高质量CsPbBrCl量子点梯度核壳（CS）结构的精确方法。表征表明，这些CS量子点呈现I型能带排列，核中溴浓度高，壳中氯浓度高。这种独特的结构导致更大的激子结合能和降低的缺陷密度，从而增强了激子辐射复合。因此，使用CS量子点的QLEDs实现了16.28%的外量子效率（EQE）、8423.35 cd/m的最大亮度以及改进的工作稳定性，超过了由均匀结构量子点（HS-QDs）制成的参考QLEDs的12.80%的EQE。这些发现提出了一种开发高质量室温合成蓝色CS量子点的策略，标志着高效纯蓝色QLEDs领域的重大进展。
