Chen Lisi, Chen Mei, Lan Yeying, Chang Yongxin, Qiao Xianfeng, Tao Chunlan, Zhao Xiaolong, Qin Dongdong, Zhang Yuwei, Zhang Baohua, Niu Li
Center for Advanced Analytical Science, Gangzhou Key Laboratory of Sensing Materials and Devices, Guangdong Engineering Technology Research Center for Photoelectric Sensing Materials and Devices, c/o School of Chemistry and Chemical Engineering, Guangzhou University, Guangzhou 510006, China.
Key Laboratory of Eco-Functional Polymer Materials, Ministry of Education, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070, China.
Mater Horiz. 2024 Nov 25;11(23):6126-6140. doi: 10.1039/d4mh00859f.
The thermally activated delayed fluorescence (TADF)-sensitized fluorescent (TSF) dye strategy has been used successfully in thermally evaporated organic light-emitting diodes (eOLEDs), but the development of solution-processed TSF-OLEDs (TSF-sOLEDs) is still very limited to date. Previously, the introduction of electronically inert shielding terminal groups for TADF sensitizer and/or fluorescent dyes was commonly used in TSF-sOLEDs, which aimed to achieve sufficient Förster energy transfer (FET) while restraining notorious Dexter energy transfer (DET) at a high doping concentration of fluorescent dyes. However, this approach has not yet enabled efficient TSF-sOLEDs owing to severe charge trapping emission (CTE) for triplet loss. In this study, by simply utilizing highly efficient boron-dipyrromethene derivatives (BODIPYs) that simultaneously feature high fluorescent quantum efficiency and narrow-band emission spectra, we developed highly efficient and super color-purity TSF-sOLEDs using a 0.1 wt% ultralow doping strategy. As confirmed, the resultant ultralow doping TSF-sOLEDs achieved sufficient FET from sensitizer to fluorochrome without noticeable CTE issues. The device achieves record maximum external quantum efficiency (EQE) and current efficiency (CE) of 21.5% and 78.8 cd A, respectively, and an ultrapure green emission with Commission International de l'Eclairage (CIE) coordinates of (0.28, 0.65). This study validates the new device architecture of ultralow doping TSF-sOLEDs, which paves the way for future development of high-resolution TSF-sOLED displays a simple solution-processed manufacturing approach.
热激活延迟荧光（TADF）敏化荧光（TSF）染料策略已成功应用于热蒸发有机发光二极管（eOLED）中，但迄今为止，溶液处理的TSF有机发光二极管（TSF-sOLED）的发展仍然非常有限。此前，在TSF-sOLED中通常采用为TADF敏化剂和/或荧光染料引入电子惰性屏蔽端基的方法，其目的是在荧光染料高掺杂浓度下实现足够的福斯特能量转移（FET），同时抑制臭名昭著的德克斯特能量转移（DET）。然而，由于三重态损失导致的严重电荷陷阱发射（CTE），这种方法尚未实现高效的TSF-sOLED。在本研究中，通过简单地利用同时具有高荧光量子效率和窄带发射光谱的高效硼二吡咯亚甲基衍生物（BODIPY），我们采用0.1 wt%的超低掺杂策略开发了高效且超色纯度的TSF-sOLED。经证实，所得的超低掺杂TSF-sOLED实现了从敏化剂到荧光染料的足够FET，而没有明显的CTE问题。该器件分别实现了创纪录的21.5%的最大外量子效率（EQE）和78.8 cd/A的电流效率（CE），以及国际照明委员会（CIE）坐标为（0.28，0.65）的超纯绿色发射。本研究验证了超低掺杂TSF-sOLED的新器件架构，为高分辨率TSF-sOLED显示器的未来发展铺平了道路 一种简单的溶液处理制造方法。
