We describe the use of organic and metal oxide semiconductors to form wide-bandgap heterojunctions to crystalline silicon. We use these semiconductors to demonstrate a heterojunction which both blocks electrons and passes holes, and a complementary heterojunction which blocks holes and passes electrons and blocks holes. The carrier transport functions are demonstrated through simple device structures as well as a photovoltaic application. In both cases, the ability to deposit layers at low-temperature (< 100 °C) is attractive for low-cost applications. The ability of organic molecules to passivate silicon surface states is also presented.