Correlation between morphology and ambipolar transport in organic field-effect transistors

TLDR: In this paper, an approach to obtain ambipolar OFET with an active layer of organic semiconductor blends using semiconducting polymers in composite with fullerene derivatives is presented. But the results of this approach are limited.

Abstract: Attaining ambipolar charge transport in organic field-effect transistors (OFET) is highly desirable from both fundamental understanding and application points of view. We present the results of an approach to obtain ambipolar OFET with an active layer of organic semiconductor blends using semiconducting polymers in composite with fullerene derivatives. Clear features of forming the super position of both hole and electron-enhanced channels for an applied gate field are observed. The present studies suggest a strong correlation of thin-film nanomorphology and ambipolar transport in field-effect devices.

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FIG. 4. sColor onlined The tapping mode AFM picture of MDMOPPV:PF:PCBMs1:1:2d blend on sad PVA, sbd BCB, and scd PVP which indicates large phase separated film on PVAsca. 200 nmd and less phase separated film on BCB and PVP.

FIG. 3. sColor onlined Tapping mode AFM picture ofsad PVA, sbd BCB, and scd PVP. All the films have smooth surfaces with a height scale of 5 nm.

FIG. 5. Typical transistor characteristics of unipolar OFET with MDMO– PPV:PF:PCBMs1:1:2d blend film coated on PVA dielectric. Inset: chemical structure of PVA.

FIG. 6. sad Typical transistor characteristics of ambipolar OFET with MDMO–PPV:PF:PCBMs1:1:2d blend film coated on BCB dielectric with hole current with pinchoff occurring atVgs above −30 V and electron current with a well-defined pinchoff atVgs above +30 V.sbd Transfer characteristics of the ambipolar OFET with hole enhancement mode and electron enhancement mode demonstrating the clear superposition of both hole- and electron-enhanced channel formation for an appliedVgs. The arrows indicate the direction sweeping ofVgs. Inset: chemical structure of BCB.

FIG. 7. Typical transistor characteristics of ambipolar OFET with MDMO– PPV:PF:PCBMs1:1:2d blend film coated on PVP dielectric demonstrating both hole enhancement mode and electron enhancement mode. Inset: chemical structure of PVP.