Zhou Yecheng, Deng Wei-Qiao, Zhang Hao-Li
State Key Laboratory of Applied Organic Chemistry (SKLAOC), College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, Gansu 730000, China.
State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Dalian 116023, China.
J Chem Phys. 2016 Sep 14;145(10):104108. doi: 10.1063/1.4962298.
Cn-[1]benzothieno[3,2-b][1]-benzothiophene (BTBT) crystals show very high hole mobilities in experiments. These high mobilities are beyond existing theory prediction. Here, we employed different quantum chemistry methods to investigate charge transfer in Cn-BTBT crystals and tried to find out the reasons for the underestimation in the theory. It was found that the hopping rate estimated by the Fermi Golden Rule is higher than that of the Marcus theory due to the high temperature approximation and failure at the classic limit. More importantly, molecular dynamics simulations revealed that the phonon induced fluctuation of electronic transfer integral is much larger than the average of the electronic transfer integral itself. Mobilities become higher if simulations implement the phonon-electron coupling. This conclusion indicates that the phonon-electron coupling promotes charge transfer in organic semi-conductors at room temperature.
Cn-[1]苯并噻吩并[3,2-b][1]苯并噻吩（BTBT）晶体在实验中表现出非常高的空穴迁移率。这些高迁移率超出了现有理论预测。在此，我们采用不同的量子化学方法研究Cn-BTBT晶体中的电荷转移，并试图找出理论低估的原因。研究发现，由于高温近似和在经典极限下的失效，费米黄金定则估计的跳跃率高于马库斯理论。更重要的是，分子动力学模拟表明，声子诱导的电子转移积分波动远大于电子转移积分本身的平均值。如果模拟考虑声子-电子耦合，迁移率会更高。这一结论表明，声子-电子耦合在室温下促进了有机半导体中的电荷转移。
