Selective Doping of Conjugated Block Copolymer for Organic Thermoelectric Applications

ABSTRACT

We demonstrate the selectively p- or n-type doping behavior of conjugated block copolymer (BCP). The poly(3-hexylthiophene)-b-poly{[N,N-9-bis(2-octyldodecyl)-naphtalene-1, 4, 5, 7-bis(dicarboximide)-2,6-diyl]-alt-5,59-(2,29-bithiophene)}, P3HT-b-P(NDI2OD-T2), has been successfully synthesized via Stille-coupling polymerization, and these p- and n-type blocks containing BCP can be doped using either F₄TCNQ or N-DMBI, generating holes or electrons as carriers, respectively. The electrical conductivity of p-doped BCP is 1.4 × 10⁻³ S·cm⁻¹, whereas, for n-doped BCP, the film conductivity is 1.7 × 10⁻⁴ S·cm⁻¹ using the four-probe method. Further, we investigate the Seebeck coefficient of doped BCP, evaluating the potential properties for thermoelectric applications. The analysis results show that the synthesized conjugated BCP can be doped either way to induce holes or electrons from a single composite polymer, and when one block is doped, the other un-doped block has no influence on the electrical conductivity. Accordingly, doping either the p- or n-type phenomenon of a single polymer is demonstrated in this study, realizing a new strategy not only for thermoelectric materials but also for overall organic electric applications.

KEYWORDS:

• Block copolymer
• Seletive doping
• Electrical conductivity
• Organic Thermoelectric

Acknowledgments

This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF), funded by the Ministry of Science, ICT & Future Planning (2017R1A1A1A05000772). This research was also supported by the Technology Innovation Program (no. 20000508, ‘Development of Superelastic Alloy Electrode Based Photovoltaic Fiber’) funded by the Ministry of Trade, Industry & Energy (MOTIE, Korea). This work was funded by the AFOSR MURI program under FA9550-12-1-0002. The MRL Shared Experimental Facilities are supported by the MRSEC Program of the NSF under Award No. DMR 1121053; a member of the NSF-funded Materials Research Facilities Network (www.mrfn.org). We thank Professor Craig J. Hawker, Professor Michael L. Chabinyc, Justin E. Cochran, Fulvio G. Brunetti, Anne M. Glaudell, and Ruth A. Schlitz at UCSB for useful discussions.

Supplementary material

Supplementary data for this article can be accessed here.

Additional information

Funding

This work was supported by the National Science Foundation [DMR 1121053]; Air Force Office of Scientific Research [FA9550-12-1-0002]; National Research Foundation of Korea [2017R1A1A1A05000772]; The Ministry of Trade, Industry & Energy of Korea [20000508].