Liao Zebing, Prodanov Maksym F, Kumar Mallem, Sergeev Aleksandr A, Song Jianxin, Kang Chengbin, Bhadra Debjyoti, Wong Kam Sing, Underwood Ian, Srivastava Abhishek Kumar
State Key Laboratory of Displays and Optoelectronics, Department of Electronics and Computer Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, 999077, P. R. China.
Centre for Display Research, Department of Electronics and Computer Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, 999077, P. R. China.
Adv Mater. 2025 Aug 6:e04559. doi: 10.1002/adma.202504559.
Quantum dot light-emitting diodes (QD-LEDs) have approached the theoretical limit of external quantum efficiency (EQE) determined by outcoupling efficiency. To achieve further improvements, novel optical designs must be explored, such as constructing optical microcavities, utilizing light scattering, or tuning the orientation of transition dipole moments (TDM). This study reports advances in red rod-in-rod quantum rods (QRs) film that exhibits a high in-plane dipole orientation of 82%, achieved through shape-induced horizontal self-alignment. Also a critical issue is discovered: the carrier leakage through irregular quantum rod films, which hinders the EQE of quantum rod light-emitting diodes (QR-LEDs) and limits its competitiveness with QD-LEDs. An equivalent circuit model comprising two diodes clearly illustrates the impacts of the leakage current within conventional QR-LED structures. By transforming the QR-LEDs device structure, balanced carrier injection and suppressed leakage current are simultaneously enhanced, achieving a red QR-LEDs with a peak EQE of 31% and a peak brightness of 110 000 cd m . Additionally, these strategies are applied to green dot-in-rod QRs, demonstrating a peak EQE of 20.2% with ultra-high luminance of 250 000 cd m . This work is expected to pave the way for further improvements in the LED performance based on anisotropic nanocrystals.
量子点发光二极管（QD-LED）已接近由外耦合效率决定的外量子效率（EQE）的理论极限。为了实现进一步的改进，必须探索新颖的光学设计，例如构建光学微腔、利用光散射或调整跃迁偶极矩（TDM）的取向。本研究报道了通过形状诱导的水平自组装实现的面内偶极取向高达82%的红色棒状量子棒（QR）薄膜的进展。同时还发现了一个关键问题：通过不规则量子棒薄膜的载流子泄漏，这阻碍了量子棒发光二极管（QR-LED）的EQE并限制了其与QD-LED的竞争力。一个由两个二极管组成的等效电路模型清楚地说明了传统QR-LED结构中泄漏电流的影响。通过改变QR-LED器件结构，同时增强了平衡载流子注入和抑制泄漏电流，实现了峰值EQE为31%、峰值亮度为110 000 cd m的红色QR-LED。此外，这些策略应用于绿色点棒状QR，展示了峰值EQE为20.2%、超高亮度为250 000 cd m的结果。这项工作有望为基于各向异性纳米晶体的LED性能的进一步改进铺平道路。
