E-Type Delayed Fluorescence of a Phosphine-Supported Cu2(μ-NAr2)2 Diamond Core: Harvesting Singlet and Triplet Excitons in OLEDs

• Published in: Journal of the American Chemical Society Vol. 132; no. 27; pp. 9499 - 9508
• Main Authors: Deaton, Joseph C, Switalski, Steven C, Kondakov, Denis Y, Young, Ralph H, Pawlik, Thomas D, Giesen, David J, Harkins, Seth B, Miller, Alex J. M, Mickenberg, Seth F, Peters, Jonas C
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 14-07-2010
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja1004575

A highly emissive bis(phosphine)diarylamido dinuclear copper(I) complex (quantum yield = 57%) was shown to exhibit E-type delayed fluorescence by variable temperature emission spectroscopy and photoluminescence decay measurement of doped vapor-deposited films. The lowest energy singlet and triplet excited states were assigned as charge transfer states on the basis of theoretical calculations and the small observed S1−T1 energy gap. Vapor-deposited OLEDs doped with the complex in the emissive layer gave a maximum external quantum efficiency of 16.1%, demonstrating that triplet excitons can be harvested very efficiently through the delayed fluorescence channel. The function of the emissive dopant in OLEDs was further probed by several physical methods, including electrically detected EPR, cyclic voltammetry, and photoluminescence in the presence of applied current.