Abstract: 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.