Carbon nanotube/silicon (CNT/Si) heterojunction solar cells represent one new architecture for photovoltaic devices. The addition of MoS2 to the devices is shown to increase the efficiency of the devices. Two structures are explored. In one case, the single wall carbon nanotubes (SWCNTs) and MoS2 flakes are mixed to make a hybrid, which is then used to make a film, while in the other case, a two layer system is used with the MoS2 deposited first followed by the SWCNTs. In all cases, the solar cell efficiency is improved largely due to significant increases in the fill factor. The rise in fill factor is due to the semiconducting nature of the MoS2, which helps with the separation of charge carriers.