The unique properties of organic semiconductors, such as flexibility and lightness, are increasingly important for information displays, lighting and energy generation. But organics suffer from both static and dynamic disorder, and this can lead to variable-range carrier hopping, which results in notoriously poor electrical properties, with low electron and hole mobilities and correspondingly short charge-diffusion lengths of less than a micrometre. Here we demonstrate a photoactive (light-responsive) organic heterostructure comprising a thin fullerene channel sandwiched between an electron-blocking layer and a blended donor:C70 fullerene heterojunction that generates charges by dissociating excitons. Centimetre-scale diffusion of electrons is observed in the fullerene channel, and this can be fitted with a simple electron diffusion model. Our experiments enable the direct measurement of charge diffusivity in organic semiconductors, which is as high as 0.83 ± 0.07 square centimetres per second in a C60 channel at room temperature. The high diffusivity of the fullerene combined with the extraordinarily long charge-recombination time yields diffusion lengths of more than 3.5 centimetres, orders of magnitude larger than expected for an organic system.

中文翻译：

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光活性有机异质结构中的厘米级电子扩散

有机半导体的独特特性，如柔韧性和轻便性，对于信息显示、照明和能源生产越来越重要。但是有机物同时受到静态和动态无序的影响，这会导致可变范围的载流子跳跃，从而导致众所周知的较差的电性能，电子和空穴迁移率低，相应的电荷扩散长度小于一微米。在这里，我们展示了一种光敏（光响应）有机异质结构，它包含夹在电子阻挡层和混合供体之间的薄富勒烯通道：C70 富勒烯异质结通过解离激子产生电荷。在富勒烯通道中观察到厘米级的电子扩散，这可以用简单的电子扩散模型拟合。我们的实验能够直接测量有机半导体中的电荷扩散率，室温下 C60 通道中的电荷扩散率高达每秒 0.83 ± 0.07 平方厘米。富勒烯的高扩散性与极长的电荷复合时间相结合，产生了超过 3.5 厘米的扩散长度，比有机系统预期的要大几个数量级。