高效二硫化钼/砷化镓异质太阳能器件研究

The discovery of graphene invites the fundamental and applied research of two dimensional materials. Two dimensional MoS2 with a band gap of 1.8 eV is one of the important member of two dimensional semiconductors and it can absorb 10% of the incident visible light, which promises many applications in the area of energy and information sciences. The photo-induced carriers can be effectively seprated and collected as the built-in voltage between MoS2 and semiconductor can be designed as the Fermi level of MoS2 can be tuned by doping or electrical gating. On the other hand, GaAs is an important traditional three dimensional semicondutor, which has a band gap of 1.42 eV. The MoS2/GaAs heterostructure can effectively absorb the incident light near the surface of heterostructure, which provides the platform for optical manipulation techniques, such as surface plasmon related techniques. This project utilizes the direct band gap nature of GaAs and use time dependent photoluminescence technique to investigate the physical pictures of the optoectronic conversion process of the MoS2/GaAs heterostructure. We will explore various techniques, such as doping, interface band gap engineering, electrical gating and surface plasmon techniques, to realize MoS2/GaAs solar cells with power conversion efficiency over 20%.

石墨烯的发现开启了二维材料基础与应用研究的大门。二维二硫化钼(MoS2)是二维半导体的重要一员，单层MoS2的禁带宽度为1.8 eV且最高可以吸收10%的可见入射光，在信息与能源领域有着广泛潜在应用。二维MoS2的费米能级能通过掺杂和电场来调整，MoS2与其他传统三维半导体形成的内建电场可以被有效调节，这也意味着MoS2/半导体异质太阳能电池的转换效率可以得到有效提升。由于GaAs具有1.42 eV的直接禁带和较大的吸光系数，MoS2/GaAs异质器件能够在近表面吸收太阳能，这为金属等离子增强等光场操控技术提供了广阔的设计空间。本项目将通过瞬态光谱等光电探测手段研究MoS2/GaAs异质器件的光电转换物理机制，探索优化MoS2/半导体异质光电器件的有效途径，利用掺杂、界面能带设计、电场调控和表面等离子体增强等技术实现转换效率超过20%的MoS2/GaAs太阳能电池。

本项目针对未来高效率、低损耗、柔性可弯曲的新型太阳能电池的需求，开展基于二维二硫化钼/砷化镓半导体异质结的新型柔性高效太阳电池关键技术研究。重点完成了大面积、高质量、连续性优良的二硫化钼材料的制备方法的研究，同时，完成了对二维二硫化钼材料费米能级调节技术、二硫化钼/砷化镓异质太阳能电池器件的设计、制备和器件机理等的研究，阐明了二硫化钼/砷化镓太阳能电池载流子的输运机制。通过二硫化钼二维半导体材料的大面积可控制备方法、二硫化钼与砷化镓太阳电池半导体材料的异质结集成技术等研究，不断优化电池界面及器件结，得到转换效率达18.65%的二硫化钼/砷化镓异质太阳能电池。同时，基于有限差分法（FDM）对二硫化钼/砷化镓太阳能电池的载流子动力学进行模拟计算，二硫化钼/砷化镓异质太阳能电池转换效率可达到23.11%，为后续进一步优化电池性能提供了理论指导，也为后续高效二硫化钼/砷化镓异质太阳能电池发展提供技术保障。