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There is a critical need to develop a method to pattern semiconducting polymers for device applications on the sub-micrometer scale. Dopant induced solubility control (DISC) patterning is a recently published method for patterning semiconductor polymers that has demonstrated sub-micron resolution. DISC relies on the sequential addition of molecular dopants (here 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ)) to the conjugated polymer. In doped areas, the conjugated polymer is protected from dissolution while in undoped areas, the polymer dissolves into solution. Here we examine factors that affect the resolution of the developed pattern. Two factors are determined to be critical to pattern resolution, the initial crystallinity of the polymer, here poly(3-hexylthiophene) (P3HT), and the quality of the development solvent. We find that dopants diffuse more readily in highly crystalline films than in amorphous films of P3HT and that dopant diffusion reduces the fidelity of the resulting pattern. We also find that the choice of development solvent affects both the fidelity of the pattern and dopant distribution within the patterned polymer domains. Finally, we show that a dopant that diffuses more slowly than F4TCNQ in the P3HT film can be used to pattern the film with higher fidelity. These results together provide a road map for optimizing additive DISC patterning for any polymer/dopant pair.
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Reversible Doping and Photo Patterning of Polymer Nanowires
Abstract Recent development of dopant induced solubility control (DISC) patterning of polymer semiconductors has enabled direct‐write optical patterning of poly‐3‐hexylthiophene (P3HT) with diffraction limited resolution. Here, the optical DISC patterning technique to the most simple circuit element, a wire, is applied. Optical patterning of P3HT and P3HT doped with the molecular dopant 2,3,5,6‐tetrafluoro‐7,7,8,8‐tetracyanoquinodimethane (F4TCNQ) wires with dimensions of 20–70 nm thickness, 200–900 nm width, and 40 μm length is demonstrated. In addition, optical patterning of wire patterns like “L” bends and “T” junctions without changing the diameter or thickness of the wires at the junctions is demonstrated. The wires themselves show up to 0.034 S cm‐1conductance when sequentially doped. It is also demonstrated that a P3HT nanowire can be doped, de‐doped, and re‐doped from solution without changing the dimension of the wire. The combined abilities to optically pattern and reversibly dope a polymer semiconductor represents a full suite of patterning steps equivalent to photolithography for inorganic semiconductors.
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- PAR ID:
- 10449608
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Electronic Materials
- Volume:
- 6
- Issue:
- 10
- ISSN:
- 2199-160X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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