College of Physics and Hebei Advanced Thin Films Laboratory, Hebei Normal University, Shijiazhuang 050016, China.
J Phys Chem B. 2011 Aug 4;115(30):9339-44. doi: 10.1021/jp2006342. Epub 2011 Jul 12.
Combining the one-dimensional tight-binding Su-Schrieffer-Heeger (SSH) model and the extended Hubbard model (EHM), the scattering and combination of oppositely charged bipolarons in conjugated polymers are investigated using a nonadiabatic evolution method. On the basis of this physical picture, bipolarons can scatter into a singlet biexcitonic state, in which two electrons and two holes are trapped together by a lattice distortion. This biexcitonic state can emit one photon to an exciton state, which can subsequently decay to the ground state. The results indicate that the scattering and combination of oppositely charged bipolarons may provide guidance for improving the internal quantum efficiency for electroluminescence to as high as 75% in polymer light-emitting diodes.
运用非绝热演化方法，将一维紧束缚 Su-Schrieffer-Heeger（SSH）模型和扩展 Hubbard 模型（EHM）相结合，研究了共轭聚合物中带相反电荷的双极化子的散射和复合。基于这一物理图像，双极化子可以散射成一个单重双激子态，其中两个电子和两个空穴被晶格变形束缚在一起。该双激子态可以发射一个光子到激子态，随后激子态可以衰减到基态。结果表明，带相反电荷的双极化子的散射和复合可能为提高聚合物发光二极管的内量子效率提供指导，使其高达 75%。
