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首页> 外文期刊>Physical review >Beyond the effective temperature: The electron ensemble at high electric fields in disordered organics
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Beyond the effective temperature: The electron ensemble at high electric fields in disordered organics

机译：超出有效温度：无序有机物中高电场下的电子集合

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摘要

Hopping between localized polaronic states, with a Gaussian distribution in energy, is regarded as the main mechanism of electric conduction in disordered organics. Several authors have recently suggested that the hopping electrons, subjected to an electric field, can be described as a homogeneous 'overheated' gas, with its "effective temperature" sufficient for a parametrization of the ensemble and the current. It is not clear how such a picture could be reconciled with the observed strongly oriented filamentization of the flow. We show, through extensive numeric simulations, that the picture is misleading as it can overestimate the electron mobility by orders of magnitude. The reason lies in deviations of the average site occupancies from the effective Boltz-mann distribution. The ensemble can be described by a distribution function with two parameters-the effective temperature and the variance of the occupancy deviations. The two are connected by a simple universal relation. The spatial structure of the occupancy deviations is found to be connected to the current filaments and its neglect is recognized as the cause for the failure of mobility calculations based on the overheated gas concept. Thus we identify those aspects, lying beyond the overheated gas picture, that are of a fundamental importance to a proper understanding of the transport in disordered organics.
机译：在能量具有高斯分布的局部极化子状态之间跳变被认为是无序有机物中导电的主要机理。几位作者最近建议，受到电场作用的跳跃电子可以被描述为一种均匀的“过热”气体，其“有效温度”足以使集合体和电流进行参数化。尚不清楚如何将这种图像与观察到的流动的强取向丝状化相一致。通过大量的数值模拟，我们证明了该图片具有误导性，因为它可能高估了几个数量级的电子迁移率。原因在于平均站点占用率与有效Boltz-mann分布存在偏差。可以通过具有两个参数的分布函数来描述集合，即有效温度和占用偏差的方差。两者通过简单的通用关系连接。占用偏差的空间结构被发现与当前的灯丝有关，而其忽略被认为是基于过热气体概念进行迁移率计算失败的原因。因此，我们确定了超出过热气体范围之外的那些方面，这些方面对于正确理解无序有机物的传输至关重要。

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