Abstract
The three-fold bridged dinuclear Cu(I) complex Cu-2(mu-I)(2)(1N-n-butyl-5-diphenyl-phosphino-1,2,4-triazole)(3), Cu2I2(P<^>N)(3), shows bright thermally activated delayed fluorescence (TADF) as well as phosphorescence at ambient temperature with a total quantum yield of 85% at an emission decay time of 7 mu s. The singlet (S1)-triplet (T-1) energy gap is as small as only 430 cm(-1) (53 meV). ...
Abstract
The three-fold bridged dinuclear Cu(I) complex Cu-2(mu-I)(2)(1N-n-butyl-5-diphenyl-phosphino-1,2,4-triazole)(3), Cu2I2(P<^>N)(3), shows bright thermally activated delayed fluorescence (TADF) as well as phosphorescence at ambient temperature with a total quantum yield of 85% at an emission decay time of 7 mu s. The singlet (S1)-triplet (T-1) energy gap is as small as only 430 cm(-1) (53 meV). Spin-orbit coupling induces a short-lived phosphorescence with a decay time of 52 mu s (T = 77 K) and a distinct zero-field splitting (ZFS) of T-1 into substates by similar to 2.5 cm(-1) (0.3 meV). Below T approximate to 10 K, effects of spin-lattice relaxation (SLR) are observed and agree with the size of ZFS. According to the combined phosphorescence and TADF, the overall emission decay time is reduced by similar to 13% as compared to the TADF-only process. The compound may potentially be applied in solution-processed OLEDs, exploiting both the singlet and triplet harvesting mechanisms.
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