Photogenerated charge carriers in double-layer organic field-effect transistor

• We fabricated ambipolar organic double-layer field-effect transistor.
• We examined photo-generated current effect on holes and electrons.
• Selective photogeneration was found depending on the absorption of each organic active layer.

Photogenerated carriers in active double-layer 3,4,9,10-perylenetetracarboxylic dianhydride/copper phthalocyanine (PTCDA/CuPc) organic field-effect transistor (OFET) have been investigated. The PTCDA and CuPc layers have n- and p-type conductivities, respectively; thus, PTCDA can be assumed as an acceptor and CuPc as a donor in the meaning of photovoltaic device. It has been found that the charges are generated in the bulk of the organic material rather than close to the organic–organic interface. Hence, it is suggested that exciton dissociation takes a place on the oxygen- and hydrogen-related defects in the organic film and supported by the molecular simulation of defects’ energy states.

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