Development of organic switchable mirrors by active control ofrefractive indices of organic semiconductor thin films

近年来，有机发光二极管、有机薄膜光伏等有机半导体器件的研究得到了长足的发展。然而，有机半导体薄膜本身的光控制从未被探索过。在本研究中，我们从分子取向和极化角度制备并分析了有机半导体薄膜，并获得了0.58的折射率差，这对于有机材料来说是一个非常大的数值。利用折射率差较大的薄膜，我们还实现了反射率为98%，反射带宽为>100 nm的有机反射镜，并证明了光传播控制和光电导率。我们相信有机半导体的光控制结果为有机半导体器件的光学设计提供了新的自由度。

The research on organic semiconductor devices, such as organic light-emitting diodes and organic thin-film photovoltaics, have been significantly developed recently. However, the light control by organic semiconductor thin-films themselves has never been explored. In this study, we fabricated and analyzed the organic semiconductor films in view of the molecular orientation and polarizability, and achieved a refractive index difference of 0.58, which is a very large value for organic materials. Using the films with the large refractive index difference, we also realized organic mirrors having a reflectivity of 98% and a reflection bandwidth of >100 nm, and demonstrated the lightpropagation control and the photoconductivity. We believe that our results of the light control by organic semiconductors offer new degrees of freedom in optical design of organicsemiconductor devices.