光调控有机半导体内电荷输运及导电特性的研究

Organic semiconductors, whose electron motion can be manipulated within an organic molecular scale, can self-assembled into devices by "bottom-up" approach with specific functionalities as the silicon-based devices, are expected to improve greatly the integrated level and the running speed of the circuits and systems. Devices that operate with photons instead of electrons as signal carriers are expected by introduction of the photochromic groups into the organic semiconductors, which will alongside attain an improved device performance, meanwhile to confer a multifunctional nature to the employed materials that is key for organic-based logic applications. In the present work, aimed at understanding the light controlled charge transport properties of organic semiconductors, we will design and synthesize the photochromic groups-containing complexes or supramolecular complexes, and use them as building blocks to construct highly-ordered nano/micro-structures or single crystals through the solution self-assembling method to perform as the photo manipulated semiconductor. Modulating the molecular structure and the arrangement within the nano/micro-structures with light stimuli, the charge transport between the molecules can be controlled to regulate the conductivity of the semiconductors, therefore to construct optoelectronic switches with high-performances. With theoretical calculations and dynamics simulations, we will study the electronic structure and charge-transport properties of the representative photo-responsive systems to understand the basic questions of the structure-property relationships.

有机半导体在一个有机分子的区域内实现对电子运动的控制，可从分子尺度进行"自下而上"的自组装构建特殊功能的器件，从而替代现行的硅基半导体器件，极大地提高电路的集成度与计算机的运行速度。将有机光致变色分子引入半导体，有望实现以光子代替电子操控的器件，进一步提升器件运行速度并赋予半导体材料更多功能特性。以光调控的有机半导体电荷传输性质为功能导向，设计分子结构及电子特性可调控的光致变色基团修饰的有机半导体分子或超分子体系组装基元，通过调节分子间作用力构筑长程有序的微纳自组装体及单晶，研究制备高性能的光响应的有机半导体器件；通过光源激发调控组装基元的结构或电子特性，从而改变或调控聚集体的有序度或微观结构，进而调控载流子传输特性，构建光电开关器件；结合量子化学理论模拟研究探索材料传输特性与微观结构之间的构效关系规律。

功能有机小分子，主要是具有π-电子离域结构的染料分子，通过分子间“弱”相互作用形成一定的聚集模式后，电子（电荷）可以在分子间发生定向迁移，从而产生单分子所不具有的光、电、热等功能性质。分子间电荷传输特性决定于分子间相互作用，即分子堆积方式，最终决定于分子结构、分子构象、分子电子结构等主要因素，因而可以通过分子修饰调控分子间相互作用而达到实现调控分子间电荷传输的目的。有机光致变色分子可以吸收光子发生分子构象或分子电子能级的改变，因而将有机光致变色分子引入分子聚集体，有望通过特定波长的光源精准调控分子堆积的方式及电荷传输路径或效率，实现光控有机半导体的特定功能。为了实现上述目标，本课题中我们提出并完成了以下几个方面的问题：1. 理解分子结构与分子排列堆积方式之间的关系，通过分子修饰调节分子间作用力，构筑长程有序的微纳自组装体及单晶；2. 聚集体或单晶中分子排列与电荷定向传输和传输效率的关系；3. 有机光致变色分子的结构异构对聚集体的有序度、微观结构及相关性质的影响；4. 聚集体中光生电荷分离、传输及其利用，有机半导体聚集结构的功能化。