Remote doping of a pentacene transistor: Control of charge transfer by molecular-level engineering

We demonstrate that holes from a p-doped N,N-'-diphenyl-N,N-'-bis(1-naphthyl)-1,1(')-biphenyl-4,4(')-diamine (alpha-NPD) layer transfer to an adjacent pentacene film. The spatial separation of carriers from dopants, or remote doping, is demonstrated with a combination of photoemission spectroscopy and current-voltage measurements for a p-doped alpha-NPD/pentacene heterojunction. Increased conductivity of the pentacene film is observed in both nongated temperature-dependent conductivity and gated thin-film transistor measurements. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3491429]