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

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 TiOX as electron-selective layers for contact passivation in c-Si solar cells are analyzed. We characterize the metal/TiOX/n-Si electron-selective contact with the contact recombination factor J0c and the contact resistivity ρc for the first time. Experimental results show that both J0c and ρc decrease after the insertion of TiOX. In addition, the effect of post-deposition rapid-thermal-annealing (RTA) at different temperatures is also evaluated. The best J0c of 5.5 pA/cm2 and the lowest ρc of 13.6 mΩ·cm2 are achieved after the RTA process. This work reveals the potential of TiOX as an electron-selective layer for contact passivation to enable high-efficiency ultra-thin c-Si solar cells with a low cost.

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