TY - JOUR
T1 - Degenerately Doped Semi-Crystalline Polymers for High Performance Thermoelectrics
AU - Lee, Yeran
AU - Park, Juhyung
AU - Son, Jaehoon
AU - Woo, Han Young
AU - Kwak, Jeonghun
N1 - Funding Information:
Y.L. and J.P. contributed equally to this work. This work was supported by the National Research Foundation (NRF) of Korea (NRF-2020M3H4A3081814, NRF-2019R1A6A1A11044070, and NRF-2017R1C1B2010776).
Funding Information:
Y.L. and J.P. contributed equally to this work. This work was supported by the National Research Foundation (NRF) of Korea (NRF‐2020M3H4A3081814, NRF‐2019R1A6A1A11044070, and NRF‐2017R1C1B2010776).
PY - 2021/2/24
Y1 - 2021/2/24
N2 - Thermoelectric (TE) energy conversion in conjugated polymers is considered a promising approach for low-energy harvesting and self-powered temperature sensing. To enhance the TE performance, it is necessary to understand the relationship between the Seebeck coefficient (α) and electrical conductivity (σ). Typical doped polymers exhibit α–σ relationship that is distinct from that of inorganic materials due to their large structural and energetic disorder, which prevents them from achieving the maximum TE power factor (PF = α2σ). Here, an ideal α–σ relationship in the Kang–Snyder model following a transport parameter s = 1 is demonstrated with two degenerately doped semi-crystalline polymers, poly[(4,4′-(bis(hexyldecylsulfanyl)methylene)cyclopenta[2,1-b:3,4-b′]dithiophene)-alt-(benzo[c][1,2,5]thiadiazole)] (PCPDTSBT) and poly[(2,5-bis(2-hexyldecyloxy)phenylene)-alt-(5,6-difluoro-4,7-di(thiophen-2-yl)benzo[c][1,2,5]thiadiazole)] (PPDT2FBT) using a sequential doping method. The results allow the realization of the PFs reaching theoretic maxima (i.e., 112.01 µW m−1 K−2 for PPDT2FBT and 49.80 µW m−1 K−2 for PCPDTSBT) and close to metallic behavior in heavily doped films. Additionally, it is shown that the PF maxima appear when the doping state switches from non-degenerate to degenerate. Strategies towards an optimal α–σ relationship enable optimization of the PF and provide an understanding of the charge transport of doped polymers.
AB - Thermoelectric (TE) energy conversion in conjugated polymers is considered a promising approach for low-energy harvesting and self-powered temperature sensing. To enhance the TE performance, it is necessary to understand the relationship between the Seebeck coefficient (α) and electrical conductivity (σ). Typical doped polymers exhibit α–σ relationship that is distinct from that of inorganic materials due to their large structural and energetic disorder, which prevents them from achieving the maximum TE power factor (PF = α2σ). Here, an ideal α–σ relationship in the Kang–Snyder model following a transport parameter s = 1 is demonstrated with two degenerately doped semi-crystalline polymers, poly[(4,4′-(bis(hexyldecylsulfanyl)methylene)cyclopenta[2,1-b:3,4-b′]dithiophene)-alt-(benzo[c][1,2,5]thiadiazole)] (PCPDTSBT) and poly[(2,5-bis(2-hexyldecyloxy)phenylene)-alt-(5,6-difluoro-4,7-di(thiophen-2-yl)benzo[c][1,2,5]thiadiazole)] (PPDT2FBT) using a sequential doping method. The results allow the realization of the PFs reaching theoretic maxima (i.e., 112.01 µW m−1 K−2 for PPDT2FBT and 49.80 µW m−1 K−2 for PCPDTSBT) and close to metallic behavior in heavily doped films. Additionally, it is shown that the PF maxima appear when the doping state switches from non-degenerate to degenerate. Strategies towards an optimal α–σ relationship enable optimization of the PF and provide an understanding of the charge transport of doped polymers.
KW - Kang–Snyder model
KW - charge transport
KW - doping
KW - organic thermoelectrics
KW - polymers
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U2 - 10.1002/adfm.202006900
DO - 10.1002/adfm.202006900
M3 - Article
AN - SCOPUS:85096997920
VL - 31
JO - Advanced Functional Materials
JF - Advanced Functional Materials
SN - 1616-301X
IS - 9
M1 - 2006900
ER -