分类： 化学 >> 物理化学 提交时间： 2017-11-05 合作期刊: 《结构化学》
摘要： In this work, the photovoltaic properties of BFBPD-PC61BM system as a promising high-performance organic solar cell (OSC) were theoretically investigated by means of quantum chemistry and molecular dynamics calculations coupled with the incoherent charge-hopping model. Moreover, the hole carrier mobility of BFBPD thin-film was also estimated with the aid of an amorphous cell including 100 BFBPD molecules. Results revealed that the BFBPD-PC61BM system possesses a middle-sized open-circuit voltage of 0.70 V, large short-circuit current density of 17.26 mA·cm-2, high fill factor of 0.846, and power conversion efficiency of 10%. With the Marcus model, in the BFBPD-PC61BM interface, the exciton-dissociation rate, kdis, was predicted to be 2.684×1013 s-1, which is as 3～5 orders of magnitude large as the decay (radiative and non-radiative) one (108～1010 s-1), indicating a high exciton-dissociation efficiency of 100% in the BFBPD-PC61BM interface. Furthermore, by the molecular dynamics simulation, the hole mobility of BFBPD thin-film was predicted to be as high as 1.265×10-2 cm2·V-1·s-1, which can be attributed to its dense packing in solid state.
分类： 物理学 >> 交叉学科物理及相关领域的科学与技术 提交时间： 2016-05-04
摘要： A non-equilibrium steady state can be characterized by a nonzero but stationary flux driven by a static external force. Under a weak external force, the drift velocity is difficult to detect because the drift motion is feeble and submerged in the intense thermal diffusion. In this article, we employ an accurate method in molecular dynamics simulation to determine the drift velocity of a particle driven by a weak external force in a one-dimensional periodic potential. With the calculated drift velocity, we found that the mobility and diffusion of the particle obey the Einstein relation, whereas their temperature dependences deviate from the Arrhenius law. A microscopic hopping mechanism was proposed to explain the non-Arrhenius behavior. Moreover, the position distribution of the particle in the potential well was found to deviate from the Boltzmann equation in a non-equilibrium steady state. The non-Boltzmann behavior may be attributed to the thermostat which introduces an effective "viscous" drag opposite to the drift direction of the particle.
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