Donor–σ–Acceptor Motifs: Thermally Activated Delayed Fluorescence Emitters with Dual Upconversion. Issue 52 (23rd November 2017)

• Record Type: Journal Article
• Authors: Geng, Yan; D'Aleo, Anthony; Inada, Ko; Cui, Lin‐Song; Kim, Jong Uk; Nakanotani, Hajime; Adachi, Chihaya
• Is Part Of: Angewandte Chemie international edition. Volume 56:Issue 52(2017)
• Page Start: 16536
• Page End: 16540
• Publication Date: 2017-11-23
• Subjects: delayed fluorescence -- donor–acceptor molecules -- hyperconjugation -- TADF lifetime -- organic light-emitting diodes; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201708876
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: A family of organic emitters with a donor–σ–acceptor (D‐σ‐A) motif is presented. Owing to the weakly coupled D‐σ‐A intramolecular charge‐transfer state, a transition from the localized excited triplet state ( 3 LE) and charge‐transfer triplet state ( 3 CT) to the charge‐transfer singlet state ( 1 CT) occurred with a small activation energy and high photoluminescence quantum efficiency. Two thermally activated delayed fluorescence (TADF) components were identified, one of which has a very short lifetime of 200–400 ns and the other a longer TADF lifetime of the order of microseconds. In particular, the two D‐σ‐A materials presented strong blue emission with TADF properties in toluene. These results will shed light on the molecular design of new TADF emitters with short delayed lifetimes. Abstract : Avoid long delays : A novel molecular design for thermally activated delayed fluorescence (TADF) emitters based on a donor–σ–acceptor motif led to short TADF decay lifetimes of less than 400 ns. Since shorter delayed lifetimes in TADF emitters are highly beneficial for device performance, this design strategy is expected to provide an effective approach to advanced TADF materials.