Bai Peng, Hu An, Liu Yang, Jin Yizheng, Gao Yunan
State Key Laboratory for Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China.
Centre for Chemistry of High-Performance & Novel Materials, State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China.
J Phys Chem Lett. 2020 Jun 4;11(11):4524-4529. doi: 10.1021/acs.jpclett.0c00748. Epub 2020 May 27.
Distribution of the transition dipole moments (TDMs) of light emitters can intrinsically affect the light out-coupling efficiency of planar light-emitting diodes (LEDs). Lacking the control of TDM distribution has limited the efficiency of nanocrystal-based LEDs to 20%. Here, we present a method that deposits uniform nanocrystal films with unity in-plane TDM distribution. Combining an inkjet printing technique and colloidal nanocrystal self-assembly, we achieved direct printing and assembly of colloidal CdSe/CdS nanoplatelets to all orient "face-down" on various substrates. With motorized translation stages, pattern printing is realized, which demonstrates the potential for integration in industrial-scale fabrication. The method is applied to achieve uniform nanoplatelet films with unity in-plane TDM distribution on zinc-oxide films, a commonly used electron-transport layer. Thus, our work paves the way to break the light out-coupling efficiency limitation of 20% in state-of-the-art nanocrystal-based LEDs, which exclusively possess an isotropic TDM distribution.
发光体的跃迁偶极矩（TDM）分布会从本质上影响平面发光二极管（LED）的光出射耦合效率。由于缺乏对TDM分布的控制，基于纳米晶体的LED效率被限制在20%。在此，我们提出一种方法，可沉积具有平面内TDM分布一致性的均匀纳米晶体薄膜。结合喷墨打印技术和胶体纳米晶体自组装，我们实现了将胶体CdSe/CdS纳米片直接打印并组装成在各种衬底上全部“面朝下”的所有取向。通过电动平移台，实现了图案打印，这展示了在工业规模制造中集成的潜力。该方法应用于在常用的电子传输层氧化锌薄膜上实现具有平面内TDM分布一致性的均匀纳米片薄膜。因此，我们的工作为突破目前最先进的、仅具有各向同性TDM分布的基于纳米晶体的LED 20%的光出射耦合效率限制铺平了道路。
