Syntheses, Crystal Structures and Photophysical Properties of Dinuclear Copper(I) Complexes Bearing Diphenylphosphino‐Substituted Benzimidazole Ligands

Three dinuclear copper(I) complexes ( 1 , 2 and 3 ) of the form [(P N)Cu] 2 (μ 2 ‐I) 2 have been designed and synthesized with 4‐diphenylphosphino‐benzimidazole (P N) derivatives. X‐ray structural analysis shows that the complexes possess one rhombohedral Cu 2 I 2 dimer that is coordinated with two P N ligands and exhibits a trans‐configuration. At 290 K, the copper complexes exhibit similar broad and featureless emission bands with peak maxima (λ max ) at 585 nm, 565 nm and 586 nm, respectively. The temperature‐dependent photophysical behaviors accompanied with the theory calculations demonstrate that 1 represents a thermally activated delayed fluorescence behavior at ambient temperature, whereas luminescence of 2 and 3 is phosphorescence. Moreover, the complexes ( 1–3 ) achieve high photoluminescence quantum yields of 36.9 %, 43.0 % and 34.0 % with relatively short emission decay times of 5.85 μs, 7.99 μs and 5.99 μs, respectively. The solution‐processed organic light‐emitting diode based on 1 achieves a peak brightness of 3325 cd m −2 and an EQE of 2.99 %.