Abstract: Silicon heterojunction (SHJ) solar cells are featured by depositing amorphous silicon (a-Si:H) thin films on the crystalline silicon (c-Si) wafers, which integrate the advantages of c-Si and a-Si:H solar cells such as simple cell structure, low process temperature, good passivation, high open-circuit voltages, low temperature coefficient, and bifacial characteristics. Therefore, SHJ solar cell is a researching/developing focus for achieving high efficiency c-Si solar cells in recent years. In the present review paper, we firstly summarize the new processes development of fabricating SHJ solar cells, which including the cleaning of wafers by ozone (O3), the deposition of a-Si:H thin films by hot wires chemical vapor deposition (HWCVD), the novel deposition method of transparent conducting oxides (TCO) films and improvement in TCO materials, and the application of new methods for metallization. Then the advanced technologies such as back junction and carrier selective passivating contacts, which are combined with SHJ solar cells, are introduced in this paper, together with the progress of thin SHJ solar cells. Further, the state-of-the-art interdigitated back contact SHJ (IBC-SHJ) and perovskite/SHJ two terminals tandem solar cells are analyzed, which show that the SHJ solar cell is the footstone for higher efficiency silicon-based solar cells.

Key words: Heterojunction; Silicon solar cells; Back junction; Carrier selective passivating contacts; Interdigitated back contact; Perovskite/SHJ two terminals tandem solar cells