拓扑绝缘体薄膜光电材料设计、特性及机理研究

拓扑绝缘体材料具有室温可调节的能带，作为光电材料能实现紫外-可见光-红外，全日光波段光电响应。本项目通过适当掺杂调控拓扑绝缘体薄膜导电性在相应基片上实现异质结，或将不同导电类型的薄膜通过原位/人工转印方式实现PN结多层膜。研究所得器件对不同波长、强度的光响应，改变薄膜成分或形貌调节光学及输运特性。研究拓扑绝缘体的表面态和体态分布对光学性质以及光电效应的影响，通过实验区分体态和表面态贡献。实现超导电子对和拓扑表面态的共存基础上研究光学、输运特性及光电效应。研究输运特性和光学特性间相互关系，探索输运性能对光电效应的影响。研究器件的光伏效应、光电转化率，揭示拓扑绝缘体材料薄膜形成的PN结光伏电池的光电转化规律及原理。采用多种半导体的多层膜型太阳能电池用于发电的光波波长更多理论转换效率提高，多层膜太阳能电池的转换效率随着技术开发还有很大的提高余地，寻找宽波段光电响应敏感且转化率高的太阳能电池材料。

Topological insulators and their doped materials have controlled gap energy at room temperature, so the PN junctions formed by topological insulator films and proper substrates can achieve a good photovoltaic effect under the broadband range from ultraviolet (UV) to near infrared (NIR) wavelengths. In this project, the conduction of topological insulator films can be controlled by doping elements, then the PN junctions can be formed by growing the topological insulator films on proper substrates, or the PN junctions are multilayer films structures formed with different kinds of electric topological insulators films, which prepared by original growth/ manual transfer methods. The transport and optical properties of these prepared PN junctions will be studied in detail. The optical responds of prepared PN junction devices will be studied with different light wavelength and intensity. The on–off responsetime of photocurrent (and photovoltage) under dark and illumination conditions will be investigated. The optical and transport properties will be studied by changing the elements and/or morphology. The relation between optical and transport properties will be investigated to learn about the effect of transport properties to optical properties. The photovoltaic effect and conversion efficiency of these devices will be investigated. The effect of photo and photoelectric properties introduced by topological insulator surface state and bulk state distribution will be studied, and the distinction between them will be done by experiments. The photo、transport and photoelectric properties will be investigated on the base of coexist of superconducting and surface state. The conversion efficiency will be improved by improving the transport properties. The conversion efficiency rule and principle of PN junctions formed by topological insulator films will be opened out. The solar cell with multilayer films structures can produce optical-electric conversion with broadband light wavelength and get high conversion efficiency in theory. So these solar cells have broader space to improve the conversion efficiency and find the good promising candidates of solar cell.