A hole-blocking silicon/titanium-oxide heterojunction for silicon photovoltaic devices and methods of forming are disclosed. The electronic device includes at least two electrodes having a current path between the two electrodes. The electronic device also includes a heterojunction formed of a titanium-oxide layer deposited over a Si layer and being disposed in the current path. The heterojunction is configured to function as a hole blocker. The first electrode may be electrically coupled to the Si layer and a second electrode may be electrically coupled to the titanium-oxide layer. The device may also include a PN junction disposed in the Si layer, in the current path. The device may also include an electron-blocking heterojunction on silicon in the current path.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
 This invention was made with government support under Grant No. DE-EE0005315 awarded by the Department of Energy and Grant No. DMR-0819860 awarded by the National Science Foundation. The government has certain rights in the invention.