TY - JOUR
T1 - High-performance n-type organic thermoelectrics enabled by modulating cyano-functionalized polythiophene backbones
AU - Wang, Junwei
AU - Ma, Suxiang
AU - Jeong, Sang Young
AU - Yang, Wanli
AU - Li, Jianfeng
AU - Han, Young Woo
AU - Feng, Kui
AU - Guo, Xugang
N1 - Publisher Copyright:
© 2024 The Royal Society of Chemistry.
PY - 2023/8/23
Y1 - 2023/8/23
N2 - The scarcity of n-type polymers with high electrical conductivity (σ) and power factor (PF) is the major challenge for organic thermoelectrics (OTEs). By integrating cyano functionalities and an intramolecular conformation lock, we herein synthesize a new electron-deficient building block, CNg4T2, bearing long 1,4,7,10-tetraoxahendecyl side chains, and then further develop two n-type polythiophene derivatives, CNg4T2-2FT and CNg4T2-CNT2, with 3,4-difluorothiophene and 3,3′-dicyano-2,2′-bithiophene as co-units, respectively. Compared with CNg4T2-2FT, CNg4T2-CNT2 features a deeper-positioned lowest unoccupied molecular orbital (LUMO) while maintaining a high degree of backbone coplanarity. As a consequence, the CNg4T2-CNT2 film with molecular dopant N-DMBI delivered an impressive σ of 13.2 S cm−1 and a high PF of up to 10.84 μW m−1 K−2, significantly outperforming CNg4T2-2FT and benchmark n-type polymer N2200 films. To the best of our knowledge, this PF of CNg4T2-CNT2 devices is the highest value for n-type polythiophenes in OTEs. Further characterizations indicate that the high performance of CNg4T2-CNT2-based devices is attributed to the high doping efficiency and ordered packing of polymer chains. Our study demonstrates that CNg4T2 is a highly appealing electron-deficient building block for n-type OTE polymers and also suggests that fine-tuning of the polymer backbone is a powerful approach to accessing high-performance n-type polymers for OTE devices.
AB - The scarcity of n-type polymers with high electrical conductivity (σ) and power factor (PF) is the major challenge for organic thermoelectrics (OTEs). By integrating cyano functionalities and an intramolecular conformation lock, we herein synthesize a new electron-deficient building block, CNg4T2, bearing long 1,4,7,10-tetraoxahendecyl side chains, and then further develop two n-type polythiophene derivatives, CNg4T2-2FT and CNg4T2-CNT2, with 3,4-difluorothiophene and 3,3′-dicyano-2,2′-bithiophene as co-units, respectively. Compared with CNg4T2-2FT, CNg4T2-CNT2 features a deeper-positioned lowest unoccupied molecular orbital (LUMO) while maintaining a high degree of backbone coplanarity. As a consequence, the CNg4T2-CNT2 film with molecular dopant N-DMBI delivered an impressive σ of 13.2 S cm−1 and a high PF of up to 10.84 μW m−1 K−2, significantly outperforming CNg4T2-2FT and benchmark n-type polymer N2200 films. To the best of our knowledge, this PF of CNg4T2-CNT2 devices is the highest value for n-type polythiophenes in OTEs. Further characterizations indicate that the high performance of CNg4T2-CNT2-based devices is attributed to the high doping efficiency and ordered packing of polymer chains. Our study demonstrates that CNg4T2 is a highly appealing electron-deficient building block for n-type OTE polymers and also suggests that fine-tuning of the polymer backbone is a powerful approach to accessing high-performance n-type polymers for OTE devices.
UR - http://www.scopus.com/inward/record.url?scp=85176754940&partnerID=8YFLogxK
U2 - 10.1039/d3fd00135k
DO - 10.1039/d3fd00135k
M3 - Article
C2 - 37965681
AN - SCOPUS:85176754940
SN - 1359-6640
VL - 250
SP - 335
EP - 347
JO - Faraday Discussions
JF - Faraday Discussions
ER -