A high mobility ambipolar field effect transistor using a 2,6-diphenylbenzo[1,2-b:4,5-b ′]diselenophene/fullerene double layer

A high mobility ambipolar field effect transistor (FET) was fabricated using a double-layer structure composed of 2,6-diphenylbenzo[1,2-b:4,5-b′]diselenophene (DPh-BDS) as a p-type layer and fullerene (C₆₀) as an n-type layer. The FET characteristics showed a large dependence on the DPh-BDS thickness, and excellent ambipolar behavior with the maximum electron and hole mobilities of μ_e = 3.0 cm² / V s and μ_h = 0.10 cm² / V s was obtained with the optimum DPh-BDS thickness of 10-20 nm. The result indicates that the μ_e of C₆₀ was considerably enhanced by keeping it away from the electron traps on the SiO₂ surface and by improving the crystalline texture of the C₆₀, which was achieved by the underlying DPh-BDS buffer layer having a rather high hole mobility on the SiO₂ layer.