Organic-inorganic heterojunction field-effect transistors

Field-effect transistors with organic-inorganic heterojunctions of molybdenum trioxide (MoO₃) /pentacene and MoO₃ /copper-phthalocyanine (CuPc) as active layers were prepared and analyzed. These transistors showed normally-on operation mode and a shift of threshold voltage comparing to the corresponding single-layer organic device. The interfacial electronic structures of MoO₃ /pentacene and MoO₃ /CuPc heterojunctions were investigated by ultraviolet photoemission spectroscopy. Significant electron energy level bending and space charge regions of high conductivity were observed at the heterojunction. Formation of the organic-inorganic heterojunctions and characteristics of the corresponding field-effect transistors were analyzed by considering charge exchange at heterojunction interfaces. © 2010 American Institute of Physics.