TY - JOUR
T1 - A Planar Cyclopentadithiophene-Benzothiadiazole-Based Copolymer with sp2-Hybridized Bis(alkylsulfanyl)methylene Substituents for Organic Thermoelectric Devices
AU - Lee, Jiae
AU - Kim, Jaeyun
AU - Nguyen, Thanh Luan
AU - Kim, Miso
AU - Park, Juhyung
AU - Lee, Yeran
AU - Hwang, Sungu
AU - Kwon, Young Wan
AU - Kwak, Jeonghun
AU - Woo, Han Young
N1 - Funding Information:
This work was supported by the National Research Foundation (NRF) of Korea (2016M1A2A2940911, 2015R1D1A1A09056905, 2015M1A2A2057506, and 2017R1C1B2010776).
Funding Information:
This work was supported by the National Research Foundation (NRF) of Korea (2016M1A2A2940911, 2015R1D1A1A09056905, 2015M1A2A2057506 and 2017R1C1B2010776).
Publisher Copyright:
© Copyright 2018 American Chemical Society.
PY - 2018/5/8
Y1 - 2018/5/8
N2 - A semicrystalline p-type thermoelectric conjugated polymer based on a polymer backbone of cyclopentadithiophene and benzothiadiazole, poly[(4,4′-(bis(hexyldecylsulfanyl)methylene)cyclopenta[2,1-b:3,4-b′]dithiophene)-alt-(benzo[c][1,2,5]thiadiazole)] (PCPDTSBT), is designed and synthesized by replacing normal alkyl side-chains with bis(alkylsulfanyl)methylene substituents. The sp2-hybridized olefinic bis(alkylsulfanyl)methylene side-chains and the sulfur-sulfur (S-S) chalcogen interactions extend a chain planarity with strong interchain packing, which is confirmed by density functional calculations and morphological studies, i.e., grazing incidence X-ray scattering measurement. The doping, electrical, morphological, and thermoelectric characteristics of PCPDTSBT are investigated by comparison with those of poly[(4,4′-bis(2-ethylhexyl)cyclopenta[2,1-b:3,4-b′]dithiophene)-alt-(benzo[c][1,2,5]thiadiazole)] (PCPDTBT) with ethylhexyl side-chains. Upon doping with a Lewis acid, B(C6F5)3, the maximum electrical conductivity (7.47 S cm-1) of PCPDTSBT is ∼1 order higher than that (0.65 S cm-1) of PCPDTBT, and the best power factor is measured to be 7.73 μW m-1 K-2 for PCPDTSBT with doping 9 mol % of B(C6F5)3. The Seebeck coefficient-electrical conductivity relation is analyzed by using a charge transport model for polymers, suggesting that the doped PCPDTSBT film has superb charge transport property based on a high crystallinity with olefinic side-chains. This study emphasizes the importance of side-chain engineering by using the sp2-hybridized olefinic substituents to modulate interchain packing, crystalline morphology, and the resulting electrical properties.
AB - A semicrystalline p-type thermoelectric conjugated polymer based on a polymer backbone of cyclopentadithiophene and benzothiadiazole, poly[(4,4′-(bis(hexyldecylsulfanyl)methylene)cyclopenta[2,1-b:3,4-b′]dithiophene)-alt-(benzo[c][1,2,5]thiadiazole)] (PCPDTSBT), is designed and synthesized by replacing normal alkyl side-chains with bis(alkylsulfanyl)methylene substituents. The sp2-hybridized olefinic bis(alkylsulfanyl)methylene side-chains and the sulfur-sulfur (S-S) chalcogen interactions extend a chain planarity with strong interchain packing, which is confirmed by density functional calculations and morphological studies, i.e., grazing incidence X-ray scattering measurement. The doping, electrical, morphological, and thermoelectric characteristics of PCPDTSBT are investigated by comparison with those of poly[(4,4′-bis(2-ethylhexyl)cyclopenta[2,1-b:3,4-b′]dithiophene)-alt-(benzo[c][1,2,5]thiadiazole)] (PCPDTBT) with ethylhexyl side-chains. Upon doping with a Lewis acid, B(C6F5)3, the maximum electrical conductivity (7.47 S cm-1) of PCPDTSBT is ∼1 order higher than that (0.65 S cm-1) of PCPDTBT, and the best power factor is measured to be 7.73 μW m-1 K-2 for PCPDTSBT with doping 9 mol % of B(C6F5)3. The Seebeck coefficient-electrical conductivity relation is analyzed by using a charge transport model for polymers, suggesting that the doped PCPDTSBT film has superb charge transport property based on a high crystallinity with olefinic side-chains. This study emphasizes the importance of side-chain engineering by using the sp2-hybridized olefinic substituents to modulate interchain packing, crystalline morphology, and the resulting electrical properties.
UR - http://www.scopus.com/inward/record.url?scp=85046638537&partnerID=8YFLogxK
U2 - 10.1021/acs.macromol.8b00419
DO - 10.1021/acs.macromol.8b00419
M3 - Article
AN - SCOPUS:85046638537
VL - 51
SP - 3360
EP - 3368
JO - Macromolecules
JF - Macromolecules
SN - 0024-9297
IS - 9
ER -