Department of Molecular Physics , Lodz University of Technology , Zeromskiego 116 , 90-924 Lodz , Poland.
Physics Department , Durham University , South Road, Durham DH1 3LE , United Kingdom.
ACS Appl Mater Interfaces. 2019 Apr 10;11(14):13460-13471. doi: 10.1021/acsami.8b18284. Epub 2019 Mar 28.
The investigation of nondoped exciplex blends of 2,4,6-tris[3-(diphenylphosphinyl)phenyl]-1,3,5-triazine (PO-T2T), working as the one-electron acceptor molecule, with different electron donors is reported. The emissions of these exciplexes span from the blue to orange-red regions, showing clear contribution from thermally activated delayed fluorescence (TADF) and delayed fluorescence originated from nongeminate recombination of charge carriers created by the dissociation of optically generated exciplexes. We focus our studies on the properties of TADF in these systems, covering in particular the physical meaning of the different transient components observed in their luminescence decays. Our results unravel the intricate role of reverse intersystem crossing due to spin-orbit coupling and possibly also due to hyperfine interactions and internal conversion, which affect the efficiency of the TADF mechanism. Remarkable performances are obtained in prototype organic light-emitting diodes fabricated with some of these blends. Green exciplex blends, in particular, exhibited the current efficiency of 60 cd A, power efficiency of 71 lm W, and external quantum efficiency of 20%. We believe that our results will contribute significantly to highlight the potential advantages of intermolecular exciplexes in the area of organic light-emitting diodes.
本文报道了 2,4,6-三[3-(二苯基膦基)苯基]-1,3,5-三嗪（PO-T2T）作为单电子受体分子与不同电子给体的非掺杂激基复合物的研究。这些激基复合物的发射范围从蓝色到橙红色，显示出热活化延迟荧光（TADF）和由光生成激基复合物的离解产生的电荷载流子的非成对复合引起的延迟荧光的明显贡献。我们专注于这些体系中 TADF 的性质研究，特别是涵盖了在它们的发光衰减中观察到的不同瞬态分量的物理意义。我们的结果揭示了由于自旋轨道耦合以及可能还有超精细相互作用和内转换而导致的反向系间窜越的复杂作用，这会影响 TADF 机制的效率。在一些这些混合物制成的原型有机发光二极管中获得了显著的性能。特别是绿色激基复合物混合物，其电流效率为 60 cd A，功率效率为 71 lm W，外量子效率为 20%。我们相信，我们的结果将有助于突出分子间激基复合物在有机发光二极管领域的潜在优势。
