Li Quanwei, Zhao Haisong, Zhao Jinyang, Cao Zhongxu, Yu Chao, Yan Shouke, Ren Zhongjie
State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology Beijing 100029 China
Department Key Laboratory of Rubber-Plastics Ministry of Education, School of Polymer Science and Engineering, Qingdao University of Science & Technology Qingdao 266042 China.
Chem Sci. 2025 Mar 10;16(15):6434-6442. doi: 10.1039/d4sc08094g. eCollection 2025 Apr 9.
Achieving efficient solution-processed ultra-deep-blue OLEDs remains a challenge. Herein, a methyl-modification strategy is proposed to overcome weak intramolecular charge transfer and the large energy gap between the singlet and triplet states (Δ ) of ultra-deep-blue through-space charge transfer (TSCT)-thermally activated delayed fluorescence (TADF) emitters. In this way, the reverse intersystem crossing (RISC) process is found to be effective from T to S and can be accelerated with the assistance of T. As a result, the ultra-deep-blue TSCT emitter 3MeCz-BO exhibits a minimized Δ of 0.02 eV, and an enhanced RISC rate of 3.71 × 10 s. Additionally, this modification can improve the solubility, enabling the fabrication of solution-processed organic light-emitting diodes (OLEDs). The maximum external quantum efficiency of the 3MeCz-BO-based solution-processed OLED reaches 10.1%, with a Commission Internationale de L'Eclairage (CIE) coordinates of (0.151, 0.051) and a luminance of 1334 cd m. This work is the first instance of developing high-performance ultra-deep-blue solution-processed TSCT-TADF OLEDs, which show comparable performance to vacuum-deposited OLEDs. Furthermore, the 3MeCz-BO-based OLED fits well within the standard Red Green Blue (sRGB) of CIE coordinates (0.15, 0.06), and is close to the CIE coordinates (0.131, 0.046) for the Rec. 2020 standard, implying its potential application in colorful display devices.
实现高效的溶液处理超深蓝色有机发光二极管（OLED）仍然是一项挑战。在此，提出了一种甲基修饰策略，以克服超深蓝色通过空间电荷转移（TSCT）-热激活延迟荧光（TADF）发射体的分子内电荷转移较弱以及单重态和三重态之间的大能量间隙（Δ）的问题。通过这种方式，发现从三重态（T）到单重态（S）的反向系间窜越（RISC）过程是有效的，并且可以在三重态的辅助下加速。结果，超深蓝色TSCT发射体3MeCz-BO表现出最小化的Δ为0.02 eV，以及增强的RISC速率为3.71×10⁶ s⁻¹。此外，这种修饰可以提高溶解性，从而能够制造溶液处理的有机发光二极管（OLED）。基于3MeCz-BO的溶液处理OLED的最大外量子效率达到10.1%，国际照明委员会（CIE）坐标为（0.151, 0.051），亮度为1334 cd m⁻²。这项工作是开发高性能超深蓝色溶液处理TSCT-TADF OLED的首个实例，其表现出与真空沉积OLED相当的性能。此外，基于3MeCz-BO的OLED很好地符合CIE坐标（0.15, 0.06）的标准红绿蓝（sRGB），并且接近Rec. 2020标准的CIE坐标（0.131, 0.046），这意味着其在彩色显示设备中的潜在应用。
