State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China.
J Chem Phys. 2019 Jan 28;150(4):044903. doi: 10.1063/1.5066563.
We show a crossover from coherent to incoherent behavior of charge transport in crystalline organic semiconductors by considering the effect of shallow traps within the dynamical disorder model. The mixed quantum-classical system is treated by the Ehrenfest dynamics method complementing with instantaneous decoherence corrections and energy relaxation, which has been shown to properly make the system close to equilibrium. The shallow traps, which are incorporated by a static diagonal disorder, are shown to play a central role in the crossover. Temperature dependence of charge-carrier mobility is shown to be changed from being negative to positive with the strength of shallow traps increasing, which implies that there is a crossover from hopping to band-like transport. A higher electric field helps to recover the charge-carrier band-like transport behavior from the traps-caused hopping transport. In this way, a unified physical picture of the charge transport in crystalline organic semiconductors is proposed.
我们通过考虑动态无序模型中浅陷阱的影响，展示了在晶体有机半导体中电荷输运从相干到非相干行为的转变。混合量子-经典系统采用 Ehrenfest 动力学方法处理，辅以瞬时退相干修正和能量弛豫，这已被证明可以使系统更接近平衡。通过静态对角无序引入的浅陷阱在转变中起着核心作用。随着浅陷阱强度的增加，电荷载流子迁移率的温度依赖性显示出从负变为正，这意味着从跳跃输运到能带输运发生了转变。更高的电场有助于从陷阱引起的跳跃输运中恢复电荷载流子的能带输运行为。通过这种方式，提出了一个晶体有机半导体中电荷输运的统一物理图像。
