Prodanov Maksym F, Mallem Kumar, Liao Zebing, Bhadra Debjyoti, Song Jianxin, Sun Meiqi, Kang Chengbin, Vashchenko Valerii V, Srivastava Abhishek K
State Key Laboratory on Advanced Displays and Optoelectronics Technologies and 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, China.
Centre for Display Research, Department of Electronics and Computer Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, 999077, China.
Adv Mater. 2025 Aug;37(33):e2503476. doi: 10.1002/adma.202503476. Epub 2025 Jun 5.
Nanocrystal-based light-emitting diodes (LEDs) are a promising technology for the next generation of flexible and large-area displays, offering high brightness, tunable narrow emission, and high display contrast. Although internal quantum efficiency (IQE) has reached unity, the external quantum efficiency (EQE) of LEDs utilizing spherical quantum dots (QDs) is limited by low light outcoupling efficiency (η). A promising approach to improve η is using horizontal alignment of nanocrystals' transition dipole moments, such as aligned quantum rods (QRs), which provide directional light emission. Though the IQE for QRs has recently improved significantly, creating efficient and bright green-emitting QRs (515-560 nm) remains a big challenge, which is essential for full-color display applications. In this study, a uniform and highly bright green-emitting CdSe/ZnCdS QRs of gradient shell structure are synthesized with minimized shell thickness and reduced Zn content, coupled with shorter organic ligands to reduce the energy barriers and enhance carriers injection. The electron leakage current at the interface between the polymeric hole transport layer (HTL) and QRs is the primary factor limiting the QRLED's performance. HTL with a higher energy offset is employed to prevent electron leakage at the organic/inorganic interface. Furthermore, is developed a bilayer HTL that enhances hole injections while minimizing electron leakage, thereby improving charge balance. The resulting QRLEDs demonstrate a record-high efficiency, with an EQE of 24%, current efficiency (CE) of 89 cd A, and maximum brightness (L) exceeding 500k cd m . Additionally, they exhibited an extended operational T lifetime of over 22k h at 100 cd m , making them well-suited for high-color-gamut display and lighting applications.
基于纳米晶体的发光二极管（LED）是下一代柔性和大面积显示器的一项很有前景的技术，具有高亮度、可调谐窄发射和高显示对比度。尽管内部量子效率（IQE）已达到100%，但利用球形量子点（QD）的LED的外部量子效率（EQE）受到低光出射效率（η）的限制。提高η的一种有前景的方法是利用纳米晶体跃迁偶极矩的水平排列，例如排列的量子棒（QR），它能提供定向发光。尽管最近QR的IQE有了显著提高，但制造高效且明亮的绿色发光QR（515-560nm）仍然是一个巨大挑战，这对于全彩显示应用至关重要。在本研究中，合成了具有梯度壳结构的均匀且高亮度的绿色发光CdSe/ZnCdS QR，其壳厚度最小化且锌含量降低，并结合了较短的有机配体以降低能垒并增强载流子注入。聚合物空穴传输层（HTL）与QR之间界面处的电子泄漏电流是限制QRLED性能的主要因素。采用具有更高能量偏移的HTL来防止有机/无机界面处的电子泄漏。此外，还开发了一种双层HTL，它在最小化电子泄漏的同时增强空穴注入，从而改善电荷平衡。所得的QRLED表现出创纪录的高效率，EQE为24%，电流效率（CE）为89cd/A，最大亮度（L）超过500k cd/m²。此外，它们在100cd/m²下的工作寿命延长至超过22k小时，使其非常适合高色域显示和照明应用。
