Titanium oxide electron-selective layers for contact passivation of thin-film crystalline silicon solar cells

摘要

In crystalline silicon (c-Si) solar cells, carrier selective contacts are among the remaining issues to be addressed in order to reach the theoretical efficiency limit. Especially in ultra-thin-film c-Si solar cells with small volumes and higher carrier concentrations, contact recombination is more critical to the overall performance. In this paper, the advantages of using TiO_x as electron-selective layers for contact passivation in c-Si solar cells are analyzed. We characterize the metal/TiO_x-Si electron-selective contact with the contact recombination factor J_(0c) and the contact resistivity p_c for the first time. Experimental results show that both J_(0c) and p_c decrease after the insertion of TiO_x. In addition, the effect of post-deposition rapid-thermal-annealing (RTA) at different temperatures is also evaluated. The best J_(0c) of 5.5 pA/cm~2 and the lowest p_c of 13.6 mΩ·cm~2 are achieved after the RTA process. This work reveals the potential of TiO_x as an electron-selective layer for contact passivation to enable high-efficiency ultra-thin c-Si solar cells with a low cost.