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Choi W, Kim S, Lee S, Jung C, Tripathi A, Lee Y, Woo HY, Lee H. Unravelling Disorder Effects on Thermoelectric Properties of Semicrystalline Polymers in a Wide Range of Doping Levels. SMALL METHODS 2023; 7:e2201145. [PMID: 36440652 DOI: 10.1002/smtd.202201145] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Indexed: 06/16/2023]
Abstract
Thermoelectric (TE) performance of a specific semicrystalline polymer is studied experimentally only in a limited range of doping levels with molecular doping methods. The doping level is finely controlled via in situ electrochemical doping in a wide range of carrier concentrations with an electrolyte ([PMIM]+ [TFSI]- )-gated organic electrochemical transistor system. Then, the charge generation/transport and TE properties of four p-type semicrystalline polymers are analyzed and their dynamic changes of crystalline morphologies and local density of states (DOS) during electrochemical doping are compared. These polymers are synthesized based on poly[(2,5-bis(2-alkyloxy)phenylene)-alt-(5,6-difluoro-4,7-di(thiophene-2-yl)benzo[c][1,2,5]thiadiazole)] by varying side chains: With oligoethylene glycol (OEG) substituents, facile p-doping is achieved because of easy penetration of TFSI- ions into the polymer matrix. However, the charge transport is hindered with longer OEG chains length because of the enhanced insulation. Therefore, with the shortest OEG substituents the electrical conductivity (30.1 S cm-1 ) and power factor (2.88 µW m-1 K-2 ) are optimized. It is observed that all polymers exhibit p- to n-type transition in Seebeck coefficients in heavily doped states, which can be achieved by electrochemical doping. These TE behaviors are interpreted based on the relation between the localized DOS band structure and molecular packing structure during electrochemical doping.
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Affiliation(s)
- Woojin Choi
- School of Materials Science and Engineering, Kookmin University, Seoul, 02707, Republic of Korea
| | - Soohyun Kim
- School of Materials Science and Engineering, Kookmin University, Seoul, 02707, Republic of Korea
| | - Soonyong Lee
- Department of Chemistry, College of Science, Korea University, Seoul, 02841, Republic of Korea
| | - Changhwa Jung
- School of Materials Science and Engineering, Kookmin University, Seoul, 02707, Republic of Korea
| | - Ayushi Tripathi
- Department of Chemistry, College of Science, Korea University, Seoul, 02841, Republic of Korea
| | - Yoonjoo Lee
- Department of Chemistry, College of Science, Korea University, Seoul, 02841, Republic of Korea
| | - Han Young Woo
- Department of Chemistry, College of Science, Korea University, Seoul, 02841, Republic of Korea
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, 02841, Republic of Korea
| | - Hyunjung Lee
- School of Materials Science and Engineering, Kookmin University, Seoul, 02707, Republic of Korea
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