TY - JOUR
T1 - Optimization of Thermoelectric Properties of Polymers by Incorporating Oligoethylene Glycol Side Chains and Sequential Solution Doping with Preannealing Treatment
AU - Tripathi, Ayushi
AU - Ko, Youngjun
AU - Kim, Miso
AU - Lee, Yeran
AU - Lee, Soonyong
AU - Park, Juhyung
AU - Kwon, Young Wan
AU - Kwak, Jeonghun
AU - Woo, Han Young
N1 - Funding Information:
A.T. and Y.K. contributed equally to this work. This work was supported by the National Research Foundation (NRF) of Korea (Grants NRF-2019R1A2C2085290, 2019R1A6A1A11044070, 2017R1C1B2010776, and 2016M1A2A2940911).
Publisher Copyright:
Copyright © 2020 American Chemical Society.
PY - 2020/8/25
Y1 - 2020/8/25
N2 - Two types of p-type thermoelectric (TE) polymers with alkyl (PCPDTSBT) and oligoethylene glycol (OEG) side chains (PCPDTSBT-A) on an sp2-hybridized olefinic bis(alkylsulfanyl)methylene-substituted cyclopentadithiophene backbone are synthesized. Interestingly, the OEG-substituted polymer, PCPDTSBT-A, exhibits significant self-doping compared to PCPDTSBT, where the polaron density of the former is 2.3 × 1016 mm-3 (vs 7.9 × 1014 mm-3 for PCPDTSBT) without external doping. Changing the side chains also induces a completely different polymer chain orientation in the PCPDTSBT-A (face-on) and PCPDTSBT (edge-on) films. The effect of doping with 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) on the morphological and TE properties of the polymers with different side chains is studied. Sequential solution doping (SQD) is performed by overcoating the preannealed polymer films with F4TCNQ solution, which affords highly effective doping without disrupting the morphology of the crystalline films, especially for PCPDTSBT-A with OEG side chains. Resulting from the synergistic effect of the OEG side chains and SQD, PCPDTSBT-A exhibits remarkably improved electrical conductivity (53.8 S cm-1) with a higher power factor (40.4 μW m-1 K-2), compared to PCPDTSBT, for which the maximum electrical conductivity is 1.4 S cm-1 and the power factor is 1.8 μW m-1 K-2. In addition, the transport coefficient of PCPDTSBT-A, determined by applying the Kang-Snyder model (2.40 × 10-2 S cm-1), is superior to that of PCPDTSBT (3.59 × 10-3 S cm-1), thereby showing the excellence of the developed strategy for improving the performance of TE polymers.
AB - Two types of p-type thermoelectric (TE) polymers with alkyl (PCPDTSBT) and oligoethylene glycol (OEG) side chains (PCPDTSBT-A) on an sp2-hybridized olefinic bis(alkylsulfanyl)methylene-substituted cyclopentadithiophene backbone are synthesized. Interestingly, the OEG-substituted polymer, PCPDTSBT-A, exhibits significant self-doping compared to PCPDTSBT, where the polaron density of the former is 2.3 × 1016 mm-3 (vs 7.9 × 1014 mm-3 for PCPDTSBT) without external doping. Changing the side chains also induces a completely different polymer chain orientation in the PCPDTSBT-A (face-on) and PCPDTSBT (edge-on) films. The effect of doping with 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) on the morphological and TE properties of the polymers with different side chains is studied. Sequential solution doping (SQD) is performed by overcoating the preannealed polymer films with F4TCNQ solution, which affords highly effective doping without disrupting the morphology of the crystalline films, especially for PCPDTSBT-A with OEG side chains. Resulting from the synergistic effect of the OEG side chains and SQD, PCPDTSBT-A exhibits remarkably improved electrical conductivity (53.8 S cm-1) with a higher power factor (40.4 μW m-1 K-2), compared to PCPDTSBT, for which the maximum electrical conductivity is 1.4 S cm-1 and the power factor is 1.8 μW m-1 K-2. In addition, the transport coefficient of PCPDTSBT-A, determined by applying the Kang-Snyder model (2.40 × 10-2 S cm-1), is superior to that of PCPDTSBT (3.59 × 10-3 S cm-1), thereby showing the excellence of the developed strategy for improving the performance of TE polymers.
UR - http://www.scopus.com/inward/record.url?scp=85089982970&partnerID=8YFLogxK
U2 - 10.1021/acs.macromol.0c01025
DO - 10.1021/acs.macromol.0c01025
M3 - Article
AN - SCOPUS:85089982970
VL - 53
SP - 7063
EP - 7072
JO - Macromolecules
JF - Macromolecules
SN - 0024-9297
IS - 16
ER -