During the last decade, transition metal oxides have been actively investigated as hole- and electron-selective materials in organic electronics due to their low-cost processing. In this study, four transition metal oxides (V₂O₅, MoO₃, WO₃, and ReO₃) with high work functions (>5 eV) were thermally evaporated as front p-type contacts in planar n-type crystalline silicon heterojunction solar cells. The concentration of oxygen vacancies in MoO_3−x was found to be dependent on film thickness and redox conditions, as determined by X-ray Photoelectron Spectroscopy. Transfer length method measurements of oxide films deposited on glass yielded high sheet resistances (~10⁹ Ω/sq), although lower values (~10⁴ Ω/sq) were measured for oxides deposited on silicon, indicating the presence of an inversion (hole rich) layer. Of the four oxide/silicon solar cells, ReO₃ was found to be unstable upon air exposure, while V₂O₅ achieved the highest open-circuit voltage (593 mV) and conversion efficiency (12.7%), followed by MoO₃ (581 mV, 12.6%) and WO₃ (570 mV, 11.8%). A short-circuit current gain of ~0.5 mA/cm² was obtained when compared to a reference amorphous silicon contact, as expected from a wider energy bandgap. Overall, these results support the viability of a simplified solar cell design, processed at low temperature and without dopants.