Verma Sandhya, Malmberg Robert, Langley Julien, Mylvaganam Kausala, Cox Nicholas, Blacque Olivier, Venkatesan Koushik
School of Natural Sciences, Macquarie University, NSW 2109, North Ryde, Australia.
Research School of Chemistry, The Australian National University,, ACT 2601, Canberra, Australia.
Chempluschem. 2025 Aug;90(8):e202500292. doi: 10.1002/cplu.202500292. Epub 2025 May 26.
Doublet emission from transition metal complexes presents a promising approach to enhance the long-term stability of organic light-emitting diodes (OLEDs) by mitigating triplet-triplet annihilation, a key factor that degrades OLED performance. In this study, a stable persistent radical (Pybtm) is incorporated as an ancillary ligand into a platinum(II) biscyclometalated complex to modulate its emission properties. Photophysical analysis of the newly synthesized and characterized complexes reveals distinct behaviors: doublet emission from the radical complex and phosphorescent emission for the neutral complex, observed both at room temperature in solution and in thin films (doped in poly(methyl methacrylate) (PMMA)) as well as in 2-Me-THF at 77 K. Detailed investigations, supported by density functional theory and time-dependent density functional theory calculations, corroborate that the emission properties are strongly dictated by the neutral and the radical ancillary ligand. Additionally, electron paramagnetic resonance spectroscopic studies verify the radical nature of these complexes, highlighting their potential for OLED applications.
过渡金属配合物的双线态发射为增强有机发光二极管（OLED）的长期稳定性提供了一种很有前景的方法，即通过减轻三重态-三重态湮灭来实现，而三重态-三重态湮灭是降低OLED性能的一个关键因素。在本研究中，一种稳定的持久性自由基（Pybtm）作为辅助配体被引入到铂（II）双环金属化配合物中，以调节其发光特性。对新合成并表征的配合物进行的光物理分析揭示了不同的行为：自由基配合物的双线态发射和中性配合物的磷光发射，在室温下的溶液和薄膜（掺杂在聚甲基丙烯酸甲酯（PMMA）中）以及77 K的2-甲基四氢呋喃中均能观察到。在密度泛函理论和含时密度泛函理论计算的支持下进行的详细研究证实，发光特性强烈地由中性和自由基辅助配体决定。此外，电子顺磁共振光谱研究证实了这些配合物的自由基性质，突出了它们在OLED应用中的潜力。
