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

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 Delta E-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/m(2), 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 CIEy = 0.08.