Trap density of states in small-molecule organic semiconductors: A quantitative comparison of thin-film transistors with single crystals

摘要: We show that it is possible to reach one of the ultimate goals organic electronics: producing field-effect transistors with trap densities as low in bulk single crystals. studied spectral density localized states band gap [trap (trap DOS)] small-molecule semiconductors derived from electrical characteristics or space-charge-limited current measurements. This was done by comparing data a large number samples including thin-film (TFT's), crystal (SC-FET's) and samples. The compilation all strongly suggests structural defects associated grain boundaries are main cause ``fast'' hole traps TFT's made vacuum-evaporated pentacene. For high-performance such rubrene essential reduce dipolar disorder caused water adsorbed on gate dielectric surface. In very densities, we sometimes observe steep increase DOS close $(l0.15\text{ }\text{eV})$ mobility edge characteristic slope 10\char21{}20 meV. It discussed what degree broadening due thermal fluctuation intermolecular transfer integral reflected this DOS. Moreover, similar hydrogenated amorphous silicon even though polycrystalline films small-molecules van der Waals-type interaction hand compared covalently bound other hand.