CuGaxM1-xS2 (M=Ti, Cr)中间带薄膜的制备、光电特性及其调控机制

Based on Wide-spectrum solar response of intermediate band materials and urgent requirements of thin film solar cells, this project aims to study on the preparation, photoelectric characteristics, and its regulatory mechanism of Ti or Cr-doped CuGaS2 intermediate band thin film. The CuGaxM1-xS2 (M=Ti, Cr) thin films prepared by ball-milling, coating and sintering. The binary metal sulfides will be used as the starting materials.The phase structure, morphology, composition and grain size of the samples will be analyzed by XRD, EDS, SEM, AFM, and so on. The effects of the processing parameters on the thin films will be investigated and the CuGaxM1-xS2 (M=Ti, Cr) thin films with controllable composition and good phase structure will be prepared. The optical band gaps, optical adsorption properties, carrier concentrations, carrier transports, and photovoltaic effects will be investigated by many photoelectric test methods. There is an impurity intermediate band forming in a thin film will be verified and its mechanism will be discussed.The regulatory mechanism of photoelectric properties will be studied by analyzing of correlations between micro-structure and photoelectric properties for the thin films. Furthermore, the physical mechanism of photoelectric effect will be revealed for the intermediate band materials. This project provides the important research foundation for introducing the intermediate band materials to the thin film solar cells.

基于半导体中间带材料可拓宽吸收光谱的特性，结合薄膜太阳能电池光吸收层高光吸收率的需求，项目旨在研究Ti, Cr掺杂的CuGaS2中间带薄膜材料的制备、光电性能及调控机制。项目采用二元硫化物为原料，通过球磨、涂覆和烧结处理制备CuGaxM1-xS2 (M=Ti, Cr)薄膜。利用XRD、XPS、EDS等方法表征薄膜的化学成分、相结构、结晶程度等特性，研究各阶段工艺条件对薄膜特性的影响规律，制备出配比可控、成相良好的CuGaxM1-xS2 (M=Ti, Cr)薄膜。在此基础之上，采用多种光电测试技术研究薄膜的光学带隙、光吸收率、载流子浓度、电子输运、光伏效应等光电特性，验证中间带的形成，并阐述其形成机理。进一步研究薄膜微观结构与其光电特性的相关性，探索薄膜光电特性的调控机制，最终揭示中间带薄膜材料光伏特性的物理机制，为中间带材料在薄膜太阳能电池中的应提供重要的研究基础。

基于半导体中间带材料与传统半导体材料相比具有高光吸收率和宽吸收光谱的特性，项目研究了Ti, Cr掺杂的CuGaS2中间带材料的制备技术、光电性能及调控机制。分别采用固相烧结、溶剂热及磁控溅射技术制备了p型的Ti, Cr掺杂的具有单一黄铜矿结构的CuGaS2化合物，并发现掺入的Ti3+或者Cr3+离子替代了Ga3+离子而形成固溶体。电学性能分析结果发现随着Ti, Cr掺杂浓度的提高，Ti, Cr掺杂的CuGaS2化合物的载流子浓度增加，电阻率下降。光学分析发现Ti, Cr掺杂的CuGaS2化合物具有更高的光吸收率和更宽的光吸收范围，并具有两个额外的子带吸收峰，验证了中间带的形成。光伏特性分析发现，由于中间带效应，中间带材料作为光吸收层可明显提高太阳电池的短路电流及光电转化效率。采用DFT理论计算结合实验结果讨论了中间带的形成机理、电子填充状态、能带结构及电子跃迁机制，为Ti, Cr掺杂的CuGaS2中间带材料在光电领域中的进一步应用提供了支持。