Investigation of the semiconductor/electrode interface in organic thin-film transistor using graphene electrodes

• Graphene films with different morphology were prepared as OTFTs electrodes.
• Rough graphene electrodes result in a discontinuous pentacene growth.
• Discontinuous and non-uniform pentacene film leads to a deteriorative mobility.

The effects of semiconductor/electrode interface on the performance of pentacene thin film transistors using graphene as electrodes are investigated. The morphology and properties of graphene electrodes were varied by controlling the number of graphene layers through a layer-by-layer (LBL) stacking method. It was discovered that increasing the stacking layers of graphene films resulted in an increased surface roughness and accompanied by a decrease in sheet resistance as well as an increase in work function. Although an increase in stacking layers provide better conductivity and energy level match between electrode and pentacene semiconductor, the spontaneous increase surface roughness disorder the growth of pentacene crystals adjacent to the electrodes and breaks the connectivity of a single-phase domain in the active film. As a result, the field-effect performance is substantially decreased by increasing the graphene films. It is shown that the morphology rather than the work function of graphene electrodes plays a dominant role in the optimization of the device performance of organic thin-film transistor using graphene electrodes.

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