Sulfone-Based Deep Blue Thermally Activated Delayed Fluorescence Emitters: Solution-Processed Organic Light-Emitting Diodes with High Efficiency and Brightness

• Published in: Chemistry of materials 2017-11, Vol.29 (21), p.9154-9161
• Main Authors: Jürgensen, Nils, Kretzschmar, Andreas, Höfle, Stefan, Freudenberg, Jan, Bunz, Uwe H. F, Hernandez-Sosa, Gerardo
• Format: Article
• Language: English
• ISSN: 0897-4756; 1520-5002
• DOI: 10.1021/acs.chemmater.7b02964

Low efficiencies of soluble blue emitter materials remain a major issue in the development of printed organic light-emitting devices. n-Alkylated carbazoles or sterically demanding ortho-substituted diphenylamines were employed as donor elements to increase solubility and to preserve blue emission of thermally activated delayed fluorescence (TADF) donor–acceptor–donor emitters employing a p-bis­(phenylsulfonyl)­benzene acceptor described in the literature. The soluble molecules exhibited increased steric hindrance of the amine donors and a small ΔE ST as low as 0.32 eV. Thermally activated delayed fluorescence occurs, and photoluminescence quantum yields of ≤82% were achieved. Application of these TADF molecules in solution-processed organic light-emitting diodes resulted in high brightnesses of ≤10000 cd/m2, current efficiencies of ≤9.5 cd/A, and external quantum efficiencies of ≤8.5%, while retaining deep blue emission ranging from 466 to 436 nm with color coordinates low as CIE y = 0.08.