Transparent and flexible organic semiconductor nanofilms with enhanced thermoelectric efficiency

Seung Hwan Lee, Hongkwan Park, Soyeon Kim, Woohyun Son, In Woo Cheong, Jung Hyun Kim

Research output: Contribution to journalArticlepeer-review

209 Citations (Scopus)


Sequential doping and dedoping increased the conductivity and optimized the oxidation level of transparent and flexible poly(3,4-ethylenedioxythiophene): poly(4-styrene sulfonic acid) (PEDOT:PSS) films, resulting in an improvement in the thermoelectric figure of merit ZT. The electrical conductivity (σ) increased from 970 to 1260 S cm-1 and the power factor from 66.5 to 70.7 μW mK-2 at the optimum concentration of the chemical dopant p-toluenesulfonic acid monohydrate (TSA). Then, the doped PEDOT:PSS films were treated with hydrazine/DMSO solutions with different hydrazine concentrations to precisely control the oxidation level. During the hydrazine/DMSO treatment (dedoping), σ of the films continuously decreased from 1647 to 783 S cm-1 due to a decrease in the carrier concentration, whereas the Seebeck coefficient (S) steeply increased from 28 to 49.3 μV K-1 at the optimum oxidation level. A power factor of 318.4 μW mK-2 (σ = 1310 S cm-1, S = 49.3 μV K-1), the highest among all existing thermoelectric nanofilms, was achieved while maintaining polymer film flexibility and transparency (88.3% of optical transmittance). In addition, the thermal conductivity (κ) of the PEDOT:PSS films decreased from 0.38 to 0.30 W mK-1 upon removal of PSS. At the lowest κ value, a high ZT value of 0.31 was achieved at room temperature.

Original languageEnglish
Pages (from-to)7288-7294
Number of pages7
JournalJournal of Materials Chemistry A
Issue number20
Publication statusPublished - 2014 May 28

All Science Journal Classification (ASJC) codes

  • General Chemistry
  • Renewable Energy, Sustainability and the Environment
  • General Materials Science


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