Photo- and electro-luminescence of three TADF binuclear Cu(i) complexes with functional tetraimine ligandsElectronic supplementary information (ESI) available: Supplementary computational and experimental data. CCDC 1528952-1528954. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c7tc00443e

Three new binuclear cuprous complexes with similar tetraimine ligands [Cu 2 (pytzph)(POP) 2 ](BF 4 ) 2 ( 1 ), [Cu 2 (pytzphcf)(POP) 2 ](BF 4 ) 2 ( 2 ) and [Cu 2 (pytzphcz)(POP) 2 ](BF 4 ) 2 ( 3 ), (pytzph = 6,6′-(1-phenyl-1,2,4-triazole-3,5-diyl)bis(2-methylpyridine), pytzphcf = 6,6′-(1-(4-(trifluoromethyl)phenyl)-1,2,4-triazole-3,5-diyl)bis(2-methylpyridine), pytzphcz = 9-(4-(3,5-bis(6-methylpyridin-2-yl)-1,2,4-triazol-1-yl)phenyl)-carbazole and POP = bis[2-(diphenylphosphine)phenyl]ether), have been synthesized and characterized in order to compare the different effects of substituent groups on the photoluminescence (PL) and electroluminescence (EL) properties. These complexes exhibit highly efficient green thermally activated delayed fluorescence (TADF) with short decay times (5.5-16 μs) and high photoluminescence quantum yields (up to 79%) at room temperature in the solid form. These complexes have essentially identical emission energy. However, the influence of the substituents on the photoluminescence and electroluminescence efficiencies is evident. Complex 3 with the carbazole group shows the highest efficiency in terms of both PL and EL, exhibiting an EQE of 8.3%, a CE of 27.1 cd A −1 and a peak brightness of 2525 cd cm −2 in the solution-processed OLED, while complex 2 with a trifluoromethyl appendage exhibits poorer quantum efficiency than the others. Three highly emissive binuclear Cu( i ) complexes have been synthesized and used as emitting dopants in highly efficient organic light-emitting devices.