共轭高分子链中电荷迁移的热效应

从理论上研究了共轭高聚物链中在电场作用下极化子运动的热效应.基于SSH模型以及通过绝热动力学演化的方法,模拟了共轭高聚物链中极化子在电场作用下从链左端向右端运动的过程.晶格受到的热扰动作用假设为通过局域的晶格范围内原子位移的随机涨落来实现.结果发现,晶格中的局域热涨落对于运动中的极化子而言等效于一个势垒.势垒高度由高分子中受到热扰动的区域的范围大小以及该区域与其周围环境的温差来决定.当分子中存在热吸收不均匀的现象时,链内极化子迁移率在低电场范围内随电场的变化遵循对数曲线变化规律.

Thermal effects on charge transport along a conjugated polymer chain

Field dependent polaron transport in a conjugated polymer chain is studied theoretically with local thermal fluctuations taken into account. Based on the Su-Schrieffer-Heeger(SSH) model combined with an adiabatic evolution method, a polaron moving from the left to the right side of the polymer chain under an applied electric field is simulated. It is assumed that thermal disturbance introduces local fluctuations in atomic displacements in a random way. The local thermal fluctuations are found to be equivalent to a potential barrier for the polaron. The range of the thermally disturbed region in the molecule and the effective temperature difference resulted from asymmetric thermal absorptions determine the height of the barrier. It is also shown that the intra-molecule polaron mobility obeys a logarithmic law in low electric field range provied that there exist asymmetric thermal absorptions within the molecule.