Research progress of compound-based dopant-free asymmetric heterogeneous contact silicon solar cell

Dopant-free asymmetric heterogeneous contact solar cells stand out as a new type of silicon-based thin-film solar cells. Since 2014, Battaglia et al., scholars from the University of California, USA, first prepared undoped asymmetric heterogeneous contact solar cells using an oxide layer as a hole-selective contact layer for n-type silicon-based cells, with a photovoltaic conversion efficiency of 14.3 %, to the current record of 23.83 % set by the Photovoltaic Materials and Devices Group, Delft University of Technology, has been developed by leaps and bounds. According to the latest simulation analysis, its theoretical efficiency is close to 29.4 %, and there is still huge room for development, thus attracting more scholars to study. The traditional silicon solar cell industry is constrained by flammable and explosive raw materials, high production costs, and environmental hazards, etc. The market expects the solar cell industry to seek green and pollution-free, low-cost, which greatly increases the necessity of research and development of new solar cells with heterogeneous contacts of undoped asymmetric silicon compounds. In this paper, we review its development, focusing on the basic principles and preparation methods of dopant-free asymmetric heterogeneous contact silicon solar cells as hole transport layer (HTL), electron transport layers (ETL), passivation layer and their selective transport. To construct a novel dopant-free, asymmetric silicon compound heterogeneous contact solar cell based on the compound. In order to have a deeper understanding of the material selection, working principle, transport mechanism and stability of this cell, and to lay a solid foundation for the construction of a new type of highly efficient and stable silicon compound heterogeneous contact solar cell.