Intrinsic photogeneration of charge carriers in organic semiconductors is generally attributed to high energy ionization or exciton dissociation by a strong electric field. Here, high bulk photoconductivity is reported in pristine pentamethine cyanine films with photocurrent onset at the band‐edge of the organic semiconductor. Single‐layer cyanine diodes with selective hole and electron contacts show linear dependence of photocurrent with reverse voltage and light intensity. Numerical drift‐diffusion simulations reveal that the linear resistor behavior stems from low and unbalanced carrier mobilities giving rise to negative space charge. Slow bimolecular recombination kinetics of photoinduced charges obtained by time delayed charge extraction measurements show strongly reduced Langevin recombination with long carrier lifetime of the order of a millisecond. Such reduced charge carrier recombination puts forward a materials concept to be exploited in photodiodes and more generally in optoelectronic devices.

中文翻译：

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具有高光电导率和较长载流子寿命的有机盐半导体

有机半导体中载流子的内在光生通常归因于强电场引起的高能电离或激子离解。在这里，在原始的五甲胺花青薄膜中据报道具有高的整体光电导性，并且在有机半导体的带边缘出现了光电流。具有选择性空穴和电子触点的单层花青二极管显示出光电流与反向电压和光强度的线性相关性。数值漂移扩散仿真表明，线性电阻器的行为源于载流子迁移率低且不平衡，从而引起负空间电荷。通过时间延迟的电荷提取测量获得的光诱导电荷的慢双分子重组动力学显示，朗格文重组显着降低，载流子寿命长达毫秒级。这种减少的电荷载流子复合提出了一种材料概念，该概念将在光电二极管中以及更普遍地在光电器件中得到利用。