Landscape of Charge Carrier Transport in Doped Poly(3-hexylthiophene): Noncontact Approach Using Ternary Combined Dielectric, Paramagnetic, and Optical Spectroscopies

Yusuke Tsutsui; Haruka Okamoto; Daisuke Sakamaki; Kazunori Sugiyasu; Masayuki Takeuchi; Shu Seki

doi:10.1021/acs.jpclett.8b01465

Landscape of Charge Carrier Transport in Doped Poly(3-hexylthiophene): Noncontact Approach Using Ternary Combined Dielectric, Paramagnetic, and Optical Spectroscopies

J Phys Chem Lett. 2018 Jul 5;9(13):3639-3645. doi: 10.1021/acs.jpclett.8b01465. Epub 2018 Jun 19.

Authors

Yusuke Tsutsui¹, Haruka Okamoto¹, Daisuke Sakamaki¹, Kazunori Sugiyasu², Masayuki Takeuchi², Shu Seki¹

Affiliations

¹ Department of Molecular Engineering , Graduate School of Engineering, Kyoto University , Nishikyo-ku, Kyoto 615-8510 , Japan.
² Molecular Design & Function Group , National Institute for Materials Science (NIMS) , 1-2-1 Sengen , Tsukuba 305-0047 , Japan.

PMID: 29911867
DOI: 10.1021/acs.jpclett.8b01465

Abstract

We report on a comprehensive measurement system for mobility and energy states of charge carriers in matter under dynamic chemical doping. The temporal evolution of the iodine doping process of poly(3-hexylthiophene) (P3HT) was monitored directly through electron paramagnetic resonance (EPR) and optical absorption spectroscopy, as well as differential electrical conductivity by the microwave conductivity measurement. The increase in conductivity was observed after the EPR intensity reached a maximum and declined thereafter, and the conductivity finally reached ∼80 S cm^-1. The carrier species changed from a paramagnetic polaron with an estimated mobility of μ_P+ ≈ 2 × 10^-3 cm² V^-1 s^-1 to an antiferromagnetic polaron pair with μ_PP+ ≈ 0.6 cm² V^-1 s^-1. The technique presented here can be a ubiquitous method for rapid and direct observation of charge carrier mobility and energy states in p-type semiconducting materials as a completely noncontact, experimental, and quantitative technique.