有机/无机界面的原子结构和电子耦合理论研究

With rapid developments of organic photovoltaic and organic information materials, intensive researches are focusing on the interaction between organic molecules and inorganic surfaces. One of the most important reasons is that organic molecules, being cheap and widely available, can manipulate the intrisic properties of the inorganic materials through molecular adsorption, forming novel functional materials and phenomena. Recently most research pays attention to explore the structure and molecular orientation at interface from the experimental point of view. Unfortunately, the microscopic mechanism of electronic interactions at the organic|inorganic interface is still unclear. In this study, we plan to take the advantage of first principles calculation to investigate configurations of organic molecules adsorbing on graphene and fullerene thin flim, respectively, and demonstrate the mechanism of the electronic interaction at the interface, to understand charge transfer and photoelectric conversion processes. More importantly, we expect to explore and design novel organic solar cell materials with the high performance through adjusting atomic structures, composition, and adsorption sites. Therefore this research focuses on microscopic picture of organic molecular adsorption, electronic coulping, light absorption and charge transport at the organic|inorganic interface.

随着有机光伏和有机信息材料的蓬勃发展，近来大量研究集中于有机分子和无机表面间的相互作用。一个重要原因在于廉价且储量巨大的有机分子在表面的吸附可以用来改变无机材料的原有物性，形成新的功能材料和新奇现象。多数研究借助于实验手段来探索界面结构和分子取向等，而界面处电子耦合的微观机理理论研究却很少。我们期望用第一原理从微观尺度上研究有机分子与石墨烯、C60薄膜界面处的原子构型、电荷转移和光电转化的过程，阐述其机理，通过改变结构、组份、吸附位等方式来探索、设计高性能新型有机太阳能电池材料。因此界面处的分子吸附、电子耦合机制、光吸收与电荷转移将成为本项研究的重点。

三年来，本课题的研究工作主要集中于分子与二维材料相互作用，二维光伏材料设计，和新型二维材料及异质界面的电子结构及性质研究上。发现MoS2表面有单个S空位缺陷存在时，分解吸附的水比不分解更加稳定，结合单层MoS2在可见光处的吸收，这些结果表明MoS2可能是一种好的光解水催化剂。设计了基于碳硅元素的新型二维光伏材料，能隙大小能够从0到2eV连续调节，这种材料在1-3eV的可见光区具有很强的光吸收系数，非常适合于新型激子型太阳能电池的应用。发现了卤化硅烯可以从小能隙的普通半导体变成拓扑绝缘体，这种结构热力学性质稳定，并且在衬底上也很稳定，得到的拓扑能隙较大（～0.2eV），因此具有很好的电子应用前景。研究了半导体异质界面的自旋轨道耦合效应及激子激发诱导的自旋光电流效应。基本完成研究目标。发表SCI论文5篇。得到高效率的新型的二维光伏活性层结构，具有半导体到拓扑绝缘体奇异电子性质转变特性、自旋电子特性的新材料。并初步尝试了新型二维光电材料分解水、解决清洁能源问题的可能性。