Developing Efficient Dinuclear Pt(II) Complexes Based on the Triphenylamine Core for High-Efficiency Solution-Processed OLEDs

The various applications of dinuclear complexes have attracted increasing attention. However, the electroluminescence efficiencies of dinuclear Pt­(II) complexes are far from satisfactory. Herein, based on the triphenylamine core, we develop four dinuclear Pt­(II) complexes that cover the emission colors from yellow to red with high photoluminescence quantum efficiencies of up to 0.79 in doped films. The solid-state structure of PyDPt is revealed by the single-crystal X-ray diffraction investigation. Besides, solution-processed OLEDs have been fabricated with different electron transport materials. With higher electron mobility and excellent hole-blocking ability, 1,3,5-tri(m-pyridin-3-ylphenyl)­benzene (TmPyPB) can help to realize good charge balance in related OLEDs. In addition, angle-dependent PL spectra reveal the preferentially horizontal orientation of these dinuclear Pt­(II) complexes in doped CBP films, which benefits the outcoupling efficiencies. Therefore, the yellow OLED based on PyDPt shows unexpected high performance with a peak current efficiency of up to 78.7 cd/A and an external quantum efficiency of up to 22.4%, which is the highest EQE reported for OLEDs based on dinuclear Pt­(II) complexes so far. This study demonstrates the great potential of developing dinuclear Pt­(II) complexes for achieving excellent electroluminescence efficiencies.