Enhancement of Short-Range Ordering of Low-Bandgap Donor–Acceptor Conjugated Polymer in Polymer/Polymer Blend Films
- Anjar Taufik HidayatAnjar Taufik HidayatDivision of Materials Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Takayama-cho, Ikoma, Nara 630-0192, JapanMore by Anjar Taufik Hidayat,
- Hiroaki Benten*Hiroaki Benten*Email: [email protected]. Phone: +81-75-383-2614. Fax: +81-75-383-2617.Division of Materials Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Takayama-cho, Ikoma, Nara 630-0192, JapanMore by Hiroaki Benten,
- Noboru OhtaNoboru OhtaJapan Synchrotron Radiation Research Institute (JASRI), 1-1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, JapanMore by Noboru Ohta,
- Yunju NaYunju NaDivision of Materials Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Takayama-cho, Ikoma, Nara 630-0192, JapanMore by Yunju Na,
- Azusa MuraokaAzusa MuraokaDepartment of Mathematical and Physical Sciences, Japan Women’s University, 2-8-1 Mejirodai, Bunkyo-ku, Tokyo 112-8681, JapanMore by Azusa Muraoka,
- Hirotaka KojimaHirotaka KojimaDivision of Materials Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Takayama-cho, Ikoma, Nara 630-0192, JapanMore by Hirotaka Kojima,
- Min-Cherl JungMin-Cherl JungDivision of Materials Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Takayama-cho, Ikoma, Nara 630-0192, JapanMore by Min-Cherl Jung, and
- Masakazu NakamuraMasakazu NakamuraDivision of Materials Science, Graduate School of Science and Technology, Nara Institute of Science and Technology, Takayama-cho, Ikoma, Nara 630-0192, JapanMore by Masakazu Nakamura
Abstract
PCPDTBT, a copolymer of cyclopentadithiophene and benzothiadiazole, is a locally ordered low-bandgap donor–acceptor conjugated polymer that has been used as a hole-transport material for polymer blend solar cells. In this study, the short-range order structure of PCPDTBT in spin-coated PCPDTBT/conjugated polymer blend films has been characterized to elucidate aggregation behaviors that arise when a locally ordered conjugated polymer is blended with other polymers. UV–vis absorption spectroscopy and grazing-incidence wide-angle X-ray scattering measurements revealed that short-range ordering of PCPDTBT is promoted when it is diluted in an amorphous conjugated polymer matrix, poly(3-methyl-4-hexylthiophene-2,5-diyl) (P3M4HT). In a PCPDTBT/P3M4HT blend film with 10 wt % PCPDTBT, the fraction of PCPDTBT chains that form aggregates increases from 51% (in neat film) to 78%, and the correlation length of the ordered PCPDTBT chains extends from 4.6 nm (in neat film) to 7.7 nm in the chain backbone direction. The polymer matrix-assisted ordering can be explained in terms of suppression of both undesired overlap and interpenetration of PCPDTBT chains; both processes can derange the self-aggregated single-chain order of PCPDTBT. This short-range ordering enhancement would be significant for the design of efficient charge carrier transport in thin-film devices such as polymer/polymer blend solar cells that use low-bandgap donor–acceptor conjugated polymers with various blend ratios as hole- and electron-transport materials.