基于太阳电池的新型掺杂C12A7透明导电薄膜制备及其光电特性研究

A new research hotspot of energy fields has focused on increasing photoelectric efficiency of solar cell, which takes advantage of up(down)-conversion luminescent property of rare earth ions.Due to the restriction of band gap for semiconductor material, silicon-based solar cell can only absorb visible light of solar spectrum. The photoelectric efficiency of solar cell may exceed Shockley - Queisser limitation using up(down)-conversion technology to modulate the incident solar spectrum. 12CaOo7Al2O3(C12A7) is a kind of broadband gap compound with cage structure, possesses optical permeability and chemical stability, and has electrical conductivity after reduction treatment. This project intends to select C12A7 transparent conductive film as host material for up(down)-conversion luminescence, the efficient up(down)-conversion luminous performance is obtained through doping rare earth ions, so the photoelectric efficiency of solar cell is improved and the cell structure is simplified. Some measurements, such as XRD, SEM, conductometer,fluorescence spectrum, rate equation, are used to analyze crystal microstructure of film, conductivity, ion interaction and up(down)-conversion luminescence property and so on. The effect of rare earth ions in RE: C12A7 on electrical performance is analyzed, and the influence of carrier motion behavior on the luminescence property is studied using quantum chemical calculation method. As a result, the theoretical foundation for application of RE:C12A7 is established.

利用稀土离子上（下）转换发光特性来提高太阳电池光电转换效率成为能源领域新的研究热点。由于半导体材料自身带隙的限制，硅基太阳电池只能吸收太阳光谱中的可见光。利用上（下）转换技术对入射太阳光谱进行调制，可使太阳电池光电转换效率至Shockley-Queisser极限以上。12CaOo7Al2O3(C12A7)是一种笼状结构的宽带隙化合物，具有光学透过性和化学稳定性，且经过还原处理后具有导电性。本项目拟选取C12A7透明导电薄膜为上（下）转换发光基质材料，通过稀土离子的掺杂获得高效上(下)转换发光性能，从而提高电池光电转换效率并简化电池结构。利用XRD、扫描电子显微镜、电导测试仪、荧光光谱和速率方程等手段分析薄膜晶体微结构、导电性、离子交互作用和上（下）转换发光特性等。采用量子化学计算方法分析RE:C12A7中稀土离子对其电学性能的影响，并研究载流子运动行为对其发光性能的影响，为其应用奠定基础。

太阳能电池历经二十余年的发展，已由7.1%的光电转换效率提高至14%。但由于半导体禁带宽度的限制，使太阳能电池只能利用可见区域光，对红外光却不能很好的吸收利用，这极大限制了太阳能电池光电转换效率的进一步提高。基于新型掺杂的C12A7透明导电薄膜和C12A7单晶太阳电池，通过对C12A7透明导电薄膜和C12A7晶体稀土掺杂，实现上转换太阳能电池，很好的将太阳能不能利用的红外光转换为可利用的可见光，提高了太阳能电池光电转换效率。本项目采用高温固相法制备用于磁控溅射的RE:C12A7陶瓷靶材，探究制备工艺对靶材成分、致密度和均匀性的影响；以RE:C12A7陶瓷为靶材，用磁控溅射法制备RE:C12A7透明导电薄膜，探究薄膜最佳制备工艺；用提拉法制备RE:C12A7单晶材料，确定晶体生长的最佳工艺条件，系统地研究Yb3+、Er3+、Ho3+和Tm3+离子掺杂C12A7单晶材料的上（下）转换荧光性能，以及稀土离子掺杂和后处理工艺对C12A7晶体材料透明导电性能的影响，并通过理论计算初步分析C12A7材料的电子结构。RE:C12A7的制备和理论分析对RE:C12A7在太阳能电池上应用有一定促进作用。为进一步拓展RE:C12A7材料的应用和提高RE:C12A7太阳能电池光电转换效率，我们将VO2薄膜与稀土掺杂C12A7晶片复合，结合了VO2对红外透过率的智能调控性能和稀土掺杂C12A7晶片上转换发光性能，制备了智能上转换发光器件；同时也合成了RE:ZnO纳米材料，并与RE:C12A7上转换发光晶片进行复合，将其优良的光电、压电和非线性光学性能与RE:C12A7上转换发光性能集于一体，拓宽了RE:C12A7上转换发光材料应用前景和应用价值，加速了太阳能电池的发展。