Optimization of Tunnel‐Junction for Perovskite/Tunnel Oxide Passivated Contact (TOPCon) Tandem Solar Cells

• Published in: Physica status solidi. A, Applications and materials science Vol. 218; no. 24
• Main Authors: Shou, Chunhui, Zheng, Jingming, Han, Qingling, Zeng, Yuheng, Ding, Waner, He, Haiyan, Liao, Mingdun, Yang, Xi, Sheng, Jiang, Yan, Baojie, Ye, Jichun
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01.12.2021
• Subjects: Annealing; Chemical vapor deposition; Crystallization; Emitters; Interdiffusion; Optimization; Passivity; perovskite silicon tandem solar cells; Perovskites; Photovoltaic cells; rapid thermal anneal; Solar cells; TOPCon; tunnel-junction; Tunnels; UV-Raman; Vapor deposition
• ISSN: 1862-6300; 1862-6319
• DOI: 10.1002/pssa.202100562

A systematic study of the formation of the tunnel‐junction for perovskite/TOPCon tandem solar cells is presented, which consists of a B‐doped poly‐Si (p+‐poly‐Si) and P‐doped poly‐Si (n+‐poly‐Si) double‐layer structure. The rear emitter double‐side TOPCon solar cell is selected as the bottom cell in tandem solar cells, where a p+‐poly‐Si/SiOx forms the rear emitter and an n+‐poly‐Si/SiOx forms the front field with the poly‐Si layer deposited by plasma‐enhanced vapor deposition (PECVD) and crystallized in a furnace. The tunnel‐junction is formed by depositing an additional B‐doped a‐Si:H (p+‐a‐Si:H) on the front n+‐poly‐Si and following a rapid thermal anneal (RTA) to partially crystallize the p+‐a‐Si:H with minimized interdiffusion of B and P. The tunnel‐junction is systematically optimized and it is found that the RTA process at 700 °C produces the optimized tunnel‐junction with the minimal contact resistivity of ≈16 mΩ cm2. The tunnel‐junction formation affects the passivation of the front field TOPCon, but the losses in the passivation quality can be recovered by a forming gas annealing. This process provides a simple and useful method for making the tunnel‐junction in perovskite/TOPCon tandem solar cells. An optimization of the tunnel‐junction for perovskite/TOPCon tandem solar cells is proposed, in which the rapid thermal anneal process is used to prevent the interdiffusion of B and P atoms and a minimal contact resistivity of ≈16 mΩ cm2 at 700 °C is achieved. In addition, the passivation loss due to rapid thermal anneal can be recovered.