Efficient Visible‐Light‐Activated Ultra‐Long Room‐Temperature Phosphorescence Triggered by Multi‐Esterification

• Published in: Angewandte Chemie International Edition 2023-12, Vol.62 (52), p.e202316647-n/a
• Main Authors: Yu, Jiahong, Sun, Zhiyu, Ma, Huili, Wang, Chengyun, Huang, Wenbin, He, Zikai, Wu, Wenjun, Hu, Honglong, Zhao, Weijun, Zhu, Wei‐Hong
• Format: Article
• Language: English
• Subjects: Afterglows; Amorphous materials; Amorphous Phosphorescent Film; Decay; Dipole moments; Encryption; Esterification; Excitation; Excitons; Hydrogen atoms; Information technology; Light; Light emitting diodes; Organic materials; Organic Room-Temperature Phosphorescence; Phosphorescence; Ultra-Long Lifetimes; Ultraviolet radiation; Visible-Light Excitation; White light
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202316647

The development of ultra‐long room‐temperature phosphorescence (UL‐RTP) in processable amorphous organic materials is highly desirable for applications in flexible displays, anti‐counterfeiting, and bio‐imaging. However, achieving efficient UL‐RTP from amorphous materials remains a challenging task, especially with activation by visible light and a bright afterglow. Here we report a general and rational molecular‐design strategy to enable efficient visible‐light‐excited UL‐RTP by multi‐esterification of a rigid large‐plane phosphorescence core. Notably, multi‐esterification minimizes the aggregation‐induced quenching and accomplishes a ′four birds with one stone′ possibility in the generation and radiation process of UL‐RTP: i) shifting the excitation from ultraviolet light to blue‐light through enhancing the transition dipole moment of low‐lying singlet‐states, ii) facilitating the intersystem crossing process through the incorporation of lone‐pair electrons, iii) boosting the decay process of long‐lived triplet excitons resulting from a significantly increased transition dipole moment, and iv) reducing the intrinsic triplet nonradiative decay by substitution of high‐frequency vibrating hydrogen atoms. All these factors synergistically contribute to the most efficient and stable visible‐light‐stimulated UL‐RTP (lifetime up to 2.01 s and efficiency up to 35.4 % upon excitation at 450 nm) in flexible films using multi‐esterified coronene, which allows high‐tech applications in single‐component time‐delayed white light‐emitting diodes and information technology based on flashlight‐activated afterglow encryption. A general and rational molecular‐design strategy has been developed to enable visible‐light excited ultra‐long room‐temperature phosphorescence (UL‐RTP). The multi‐esterification strategy boosts transition dipole moments, leading to the most efficient UL‐RTP in flexible films upon excitation with blue light, which allows high‐tech applications in time‐delayed white LEDs and flashlight‐activated afterglow encryption.