Enhanced carrier collection in p-Ni1 − xO:Li/n-Si heterojunction solar cells using LiF/Al electrodes

•LiF/Al stack is an efficient Ohmic contact method for non-heavy doped n-type Si.•The conversion efficiency of cell increases from 4.20% to 6.31%.•The carrier transport mechanism is dipole-assisted tunneling.

This study confirms that a LiF/Al (LiF thickness = 15 Å) stack is an efficient Ohmic contact method for use in p-Ni1 − xO:Li/n-Si heterojunction solar cell applications. The maximal conversion efficiency obtained was 6.31%, which was 2.1% greater compared with that of Al-only electrode cell. Temperature-dependent current–voltage measurements confirmed that the carrier transport mechanism was dipole-assisted tunneling at the interface. The insertion of LiF acted as an effective Ohmic contact method and also assisted the back surface passivation.