Ambipolar organic phototransistor

We report on the fabrication and characterization of ambipolar organic phototransistors based on amorphous thin films of donor/ acceptor dyad N-[7-(NN-diphenylamino)-9,9'-spirobifluoren-2-yl]-N'-(2,5-di-tert-butylphenyl)-3,4:9,10-perylenetetracarboxylicdiimide. The mechanism of light enhanced photocurrent is based on photoinduced charge transfer between the donor and the acceptor unit. The photoresponsivity of up to 0.2 A/W can be obtained. The drain current is significantly increased by a factor of nearly 100 as the light is used as an additional control parameter, making the device interesting for sensor applications. (c) 2006 Elsevier B.V. All rights reserved.