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.双核配合物的各类应用已受到日益广泛的关注。然而，双核铂(II)配合物的电致发光效率仍远未达到理想水平。本文以三苯胺为核心，开发了四种双核铂(II)配合物，其发光颜色涵盖黄光至红光区间，在掺杂薄膜中的光致发光量子效率最高可达0.79。通过单晶X射线衍射表征，揭示了PyDPt的固态晶体结构。此外，我们采用不同电子传输材料制备了溶液加工型有机发光二极管（Organic Light-Emitting Diode, OLED）。其中，1,3,5-三(间-3-吡啶基苯基)苯（1,3,5-tri(m-pyridin-3-ylphenyl)benzene, TmPyPB）兼具较高的电子迁移率与优异的空穴阻挡能力，可助力相关OLED器件实现良好的电荷平衡。另外，角度分辨光致发光（Photoluminescence, PL）光谱测试表明，此类双核铂(II)配合物在掺杂的CBP薄膜中呈现优先水平取向，这有利于提升器件的光取出效率。基于PyDPt的黄色OLED器件展现出优异的综合性能：峰值电流效率最高可达78.7 cd/A，外量子效率（External Quantum Efficiency, EQE）最高达22.4%，为迄今为止已报道的双核铂(II)配合物基OLED器件的最高外量子效率值。本研究证实了开发双核铂(II)配合物以实现优异电致发光效率的巨大潜力。