Pander Piotr, Daniels Ruth, Zaytsev Andrey V, Horn Ashleigh, Sil Amit, Penfold Thomas J, Williams J A Gareth, Kozhevnikov Valery N, Dias Fernando B
Department of Physics, Durham University South Road Durham DH1 3LE UK
Department of Applied Sciences, Northumbria University Ellison Building Newcastle upon Tyne NE1 8ST UK
Chem Sci. 2021 Mar 22;12(17):6172-6180. doi: 10.1039/d1sc00160d.
A novel dinuclear platinum(ii) complex featuring a ditopic, bis-tetradentate ligand has been prepared. The ligand offers each metal ion a planar ^^^ coordination environment, with the two metal ions bound to the nitrogen atoms of a bridging pyrimidine unit. The complex is brightly luminescent in the red region of the spectrum with a photoluminescence quantum yield of 83% in deoxygenated methylcyclohexane solution at ambient temperature, and shows a remarkably short excited state lifetime of 2.1 μs. These properties are the result of an unusually high radiative rate constant of around 4 × 10 s, a value which is comparable to that of the very best performing Ir(iii) complexes. This unusual behaviour is the result of efficient thermally activated reverse intersystem crossing, promoted by a small singlet-triplet energy difference of only 69 ± 3 meV. The complex was incorporated into solution-processed OLEDs achieving EQE = 7.4%. We believe this to be the first fully evidenced report of a Pt(ii) complex showing thermally activated delayed fluorescence (TADF) at room temperature, and indeed of a Pt(ii)-based delayed fluorescence emitter to be incorporated into an OLED.
制备了一种具有双齿、双四齿配体的新型双核铂（II）配合物。该配体为每个金属离子提供了一个平面配位环境，两个金属离子与一个桥连嘧啶单元的氮原子相连。该配合物在光谱的红色区域发出明亮的光，在室温下脱氧甲基环己烷溶液中的光致发光量子产率为83%，并且显示出2.1 μs的非常短的激发态寿命。这些性质是由于约4×10 s的异常高的辐射速率常数导致的，该值与性能最佳的Ir（III）配合物相当。这种异常行为是由仅69±3 meV的小单线态-三线态能量差促进的有效热激活反向系间窜越的结果。该配合物被整合到溶液处理的OLED中，实现了EQE = 7.4%。我们认为这是关于Pt（II）配合物在室温下显示热激活延迟荧光（TADF）的第一份有充分证据的报告，实际上也是关于一种基于Pt（II）的延迟荧光发射体被整合到OLED中的报告。
