Thermally Activated Delayed Fluorescence in an Organic Cocrystal: Narrowing the Singlet–Triplet Energy Gap via Charge Transfer. (8th July 2019)

• Record Type: Journal Article
• Authors: Sun, Lingjie; Hua, Weijie; Liu, Yang; Tian, Guangjun; Chen, Mingxi; Chen, Mingxing; Yang, Fangxu; Wang, Shufeng; Zhang, Xiaotao; Luo, Yi; Hu, Wenping
• Is Part Of: Angewandte Chemie. Volume 131:Number 33(2019)
• Page Start: 11433
• Page End: 11438
• Publication Date: 2019-07-08
• Subjects: Cokristall-Engineering -- Dichtefunktionalrechungen -- Intermolekularer Ladungstransfer -- Schwingungskopplung -- Thermisch aktivierte verzögerte Fluoreszenz; Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.201904427
• Languages: English
• ISSNs: 0044-8249

Abstract

Abstract: Harvesting non‐emissive spin‐triplet charge‐transfer (CT) excitons of organic semiconductors is fundamentally important for increasing the operation efficiency of future devices. Here we observe thermally activated delayed fluorescence (TADF) in a 1:2 CT cocrystal of trans ‐1, 2‐diphenylethylene (TSB) and 1, 2, 4, 5‐tetracyanobenzene (TCNB). This cocrystal system is characterized by absorption spectroscopy, variable‐temperature steady‐state and time‐resolved photoluminescence spectroscopy, single‐crystal X‐ray diffraction, and first‐principles calculations. These data reveal that intermolecular CT in cocrystal narrows the singlet–triplet energy gap and therefore facilitates reverse intersystem crossing (RISC) for TADF. These findings open up a new way for the future design and development of novel TADF materials. Abstract : Eile mit Weile : Cokristalle aus trans ‐1, 2‐Diphenylethylen (TSB) und 1, 2, 4, 5‐Tetracyanbenzol (TCNB) zeigen thermisch aktivierte verzögerte Fluoreszenz (TADF). Der intermolekulare Ladungstransfer in Cokristallen trägt zu einer kleinen Singulett‐Triplett‐Energielücke bei und ist, zusammen mit dem kristallinen Zustand in Cokristallen, verantwortlich für die TADF.