Carrier Mobilities in Amorphous Organic Semiconductor Films Prepared at Various Film Formation Processes

摘要

The hole mobility of an organic semiconductor film that consists of N,N’-di(1-naphthyl)-N,N’-diphenyl-benzidine (α-NPD) is evaluated at various filmformation processes, such as vacuum deposition and capillary injection. Themobility varies with the film formation process. From the temperature dependenceof mobility, the Poole-Frenkel model and disorder model are discussed.From the analysis based on the Poole-Frenkel model, activation energies of thevacuum-deposited film, the slowly cooled-melted film, and the rapidly cooledmeltedfilm are 0.28, 0.20, and 0.40 eV, respectively. This result suggests thatorganic semiconductor thin films formed by different film formation methodshave different molecular aggregation states.