Organic Long Persistent Luminescence Through In Situ Generation of Cuprous(I) Ion Pairs in Ionic Solids

• Published in: Angewandte Chemie International Edition Vol. 60; no. 46; pp. 24437 - 24442
• Main Authors: Liang, Xiao, Luo, Xu‐Feng, Yan, Zhi‐Ping, Zheng, You‐Xuan, Zuo, Jing‐Lin
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 08.11.2021
• Edition: International ed. in English
• Subjects: afterglow duration; Cations; Coordination compounds; CuI complex; Ion pairs; Luminescence; organic long persistent luminescence; organic room temperature phosphorescence; reaction mechanisms
• DOI: 10.1002/anie.202110251
• ISSN: 1433-7851

Recent development of most organic long persistent luminescence (OLPL) systems employed binary or tertiary doping. However, the design strategies towards OLPL materials with hour‐long afterglow duration are still quite limited. Here, we propose a novel OLPL system through melt‐casting method with 0.1 mol % of CuI complexes: 2,2′‐bis(diphenylphosphino)‐1,1′‐binaphthyl BINAP‐CuX (X=Cl, Br and I) doped into the triphenylphosphine (TPP) host. The charge separation was initiated prior to excitation through host coordination with CuI complexes, resulting in semi‐free halogen ions and in situ generated CuI cations, which forms TPP + BINAP‐CuX ionic pairs and subsequently ionic solids. The OLPL lifetime can be readily modulated by different halogen atoms and the afterglow can last up to more than 3 hours perceivable to human eyes. This is a rare example of OLPL initiated through host‐guest coordination that could potentially expand the definition of OLPL systems and design strategies. An organic long persistent luminescence (OLPL) system based on in situ generated ionic pairs with CuI centers is proposed and demonstrated. Intermediates are proposed and verified through a series of carefully designed experiments. The afterglow of corresponding blends can last more than 3 hours, thus this mechanism is the first to incorporate CuI ions in OLPL systems.