新型黄铜矿结构晶体ZnSiP2的生长及其光电转换性能研究

Tandem solar cell technology is a unique multi-junction fabrication method to improve the conversion efficiency and it plays a significant role to reduce the cost of conventional silicon solar cells. The top layer in the multi-junction determines the efficiency. Therefore, the research on development of top layer has highly been attracted to fabricate the solar cells with high efficiency to cost ratio, eco-friendly, long life-time, and good stabilization. Zinc silicon phosphide (ZnSiP2) is a chalcopyrite type crystal structure, and forms very small lattice mismatch (0.5%) with silicon substrate. The ZnSiP2 is non-toxic, low cost material with energy gap of ~2.0 eV, suitable for visible light absorption. These properties favor for the fabrication of silicon tandem solar cell with ZnSiP2 as a top layer. This research proposal focuses on two parts: (1) Preparation of large and uniform sized ZnSiP2 film using liquid phase epitaxy method. (2) Fabrication and photovoltaic studies of ZnSiP2 top-layered silicon tandem solar cell. The thin film of ZnSiP2 will be prepared based on the investigation of dissolution and crystallization properties of ZnSiP2 in Sn and Zn solution. Influence of different crystal growth parameters on growth rate and crystalline quality, and effect of impurities on the semiconductor properties of ZnSiP2 will be deeply studied through this project. Furthermore, the photovoltaic properties of proposed material against different film thicknesses and semiconductor properties will be investigated. This project will promote the theory and technique of liquid phase epitaxy method, and develop a novel ZnSiP2/Si tandem solar cell.

叠层技术是进一步提高Si太阳能电池的光电转换效率、降低成本的有效方法。开发成本低廉、环境友好、寿命长久、性能稳定，且具有高的光电转换效率的顶层电池材料，是Si叠层太阳能电池研究的重要课题。黄铜矿结构的ZnSiP2晶体与Si的晶格失配非常小(0.5%)，且能隙约为2.0 eV，对可见光具有强的吸收，是一种极具潜力的新型Si叠层太阳能电池的顶层电池材料。本课题以新型ZnSiP2单晶薄膜的制备和光电性能评价为主要研究内容，在探索ZnSiP2在Zn和Sn助熔剂中的溶解和析晶特性的基础上，拟采用液相外延法生长ZnSiP2单晶薄膜，深入探寻晶体生长参数与生长速度和结晶品质的关系，详细研究掺杂种类和浓度对ZnSiP2半导体性能的影响，研制ZnSiP2/Si叠层太阳能电池并全面评价其光电转换性能。本项目的开展对促进液相外延晶体生长的理论和技术，开发新型的Si叠层太阳能电池具有重要的科学意义和实用价值。

新型Si-P系列化合物是一类性能优异的新型高效光电功能晶体材料。按照课题研究计划，我们开展了ZnSiP2晶体助溶剂法生长工艺和ZnSiP2薄膜液相外延法生长工艺的研究。采用助溶剂法可以安全，稳定，批量生长出ZnSiP2晶体，国际上首次采用液相外延法成功地在Si（100）上生长了一层ZnSiP2外延薄膜，通过工艺的优化，可以稳定的得到ZnSiP2/Si异质结。此外，我们对薄膜的形貌，厚度以及成分进行了表征，分析了薄膜与衬底之间的外延关系。探索了薄膜表面岛状晶体在不同生长条件下的形貌变化，并对ZnSiP2/Si异质结的光学以及电学性质进行了研究。同时，我们对ZnSiP2晶体的其它应用进行了探索，表征了其在光催化，超级电容器方面的性能。