journal article·2026-08Open access

Thermoelectric enhancement in PEDOT:PSS inks driven by PSS molecular weight tailoring

João H.C. Bocchi, Germán D. Gómez Higuita, Gustavo G. Dalkiranis, Gregório C. Faria

Synthetic Metals· Volume 320

Abstract

The growing demand for electricity aggravates global warming and reinforces the need for affordable and sustainable energy sources. Thermoelectric generators, which convert waste heat into electricity, have attracted increasing attention as sustainable energy technologies. Conductive polymers such as poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) are promising candidates due to their low cost, flexibility, and low toxicity. In this study, we investigate the influence of the molecular weight (Mw) of poly(4-styrene sulfonic acid) (PSS) on the thermoelectric properties of PEDOT:PSS inks. The Seebeck coefficient (S) and electrical conductivity (σ) were evaluated to determine the power factor (PF = S 2 · σ). Increasing the Mw of PSS promotes the formation of larger interconnected PEDOT-rich domains, enhancing charge transport and improving the thermoelectric performance. The ink synthesized with higher molecular weight PSS (157 kDa) exhibited the best performance, reaching a power factor of (1.3 ± 0.1) μW/(K 2 ·m), approximately 30 times higher than that of the ink with lower Mw PSS (23 kDa).
Source: openalex_inverted_index · Quality: baseline

Research context

OpenAlex topics: Conducting polymers and applications · Advanced Thermoelectric Materials and Devices · Advanced Sensor and Energy Harvesting Materials

SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.

References (68)

Show source-provided references
1. Enerdata · Glob. Energy Stat. Yearb. 2023 · 2023
2. Empresa de Pesquisa Energética (EPE) · Minist. ério De. Minas e Energ. Anu. ário Estat. ístico De. Energ. Elétrica · 2023
3. Agência Internacional de Energia (IEA), World Energy Outlook, (2022). 〈https://www.iea.org/reports/world-energy-outlook-2022〉 (accessed January 12, 2025).
4. Theoretical efficiency limits for energy conversion devices10.1016/j.energy.2010.01.024 ↗
5. Waste heat: the dominating root cause of current global warming10.1186/s40068-020-00169-2 ↗
6. WASTE HEAT RECOVERY TECHNOLOGIES: PATHWAY TO SUSTAINABLE ENERGY DEVELOPMENT10.18186/thermal.850796 ↗
7. Seebeck T.J., Ueber Den Magnetismus Der Galvanischen Kette, der Wissenschaften, Berlim, 1822. 〈https://play.google.com/books/reader?id=G-JYAAAAYAAJ&pg=GBS.PP8&hl=pt〉. (accessed January 14, 2025).
8. Thermoelectric Materials for Space and Automotive Power Generation10.1557/mrs2006.49 ↗
9. Measurement system to determine the Seebeck coefficient and electrical conductivity of thin films10.1109/TIM.2025.3553254 ↗
10. Review of thermoelectric geometry and structure optimization for performance enhancement10.1016/j.apenergy.2020.115075 ↗
11. Ueber die magnetische Polarisation der Metalle und Erze durch Temperatur-Differenz10.1002/andp.18260820202 ↗
12. Cooling, Heating, Generating Power, and Recovering Waste Heat with Thermoelectric Systems10.1126/science.1158899 ↗
13. A Self-Powered Flexible Thermoelectric Sensor and Its Application on the Basis of the Hollow PEDOT:PSS Fiber10.3390/polym12030553 ↗
14. ROWE · 2005
15. N. ASHCROFT, Física do estado sólido, Cengage Learning, São Paulo, 2010.
16. A Review on Organic Polymer-Based Thermoelectric Materials10.1007/s10924-016-0895-z ↗
17. Review on Polymers for Thermoelectric Applications10.3390/ma7096701 ↗
18. Thermoelectric Cooling and Power Generation10.1126/science.285.5428.703 ↗
19. Testing the validity of the Wiedemann–Franz law for metals and alloys at high pressures10.1063/5.0234126 ↗
20. Kittel · 2004
21. Complex thermoelectric materials10.1038/nmat2090 ↗
22. Review—Organic Materials for Thermoelectric Energy Generation10.1149/2.0121703jss ↗
23. Wearable thermoelectric generator with vertically aligned PEDOT:PSS and carbon nanotubes thermoelements for energy harvesting10.1002/er.8283 ↗
24. Flexible hybrid thermoelectric films made of bismuth telluride-PEDOT:PSS composites enabled by freezing-thawing process and simple chemical treatment
25. Automobile exhaust flexible thermoelectric harvester enabled by liquid metal-based heatsink10.1016/j.enconman.2024.118826 ↗
26. Advancements in thermoelectric materials: Emerging trends in organic, inorganic systems, and material informatics10.1016/j.jallcom.2025.180661 ↗
27. PEDOT:PSS-based electronic materials: Preparation, performance tuning, processing, applications, and future prospect10.1016/j.progpolymsci.2025.101990 ↗
28. PEDOT:PSS-based electrochromic materials for flexible and stretchable devices
29. Elschner · 2010
30. Reynolds · 2019
31. Exceptional thermoelectric properties of flexible organic−inorganic hybrids with monodispersed and periodic nanophase10.1038/s41467-018-06251-9 ↗
32. Simultaneous enhancement of electrical conductivity and seebeck coefficient in organic thermoelectric SWNT/PEDOT:PSS nanocomposites10.1016/j.carbon.2019.04.007 ↗
33. Engineered doping of organic semiconductors for enhanced thermoelectric efficiency10.1038/nmat3635 ↗
34. Influence of the molecular weight and size distribution of PSS on mixed ionic-electronic transport in PEDOT:PSS10.1039/D2PY00271J ↗
35. The mechanism of enhancing the conductivity of PEDOT: PSS films through molecular weight optimization of PSS
36. The Thermoelectric Performance of Poly(3,4-ethylenedi oxythiophene)/Poly(4-styrenesulfonate) Thin Films10.1007/s11664-009-0821-4 ↗
37. Organic Semiconductors for Thermoelectric Applications10.1007/s11664-010-1271-8 ↗
38. Thermoelectric Performance of Poly(3,4-Ethylenedioxy-thiophene)/Poly(Styrenesulfonate) Pellets and Films10.1007/s11664-010-1494-8 ↗
39. A facile dedoping approach for effectively tuning thermoelectricity and acidity of PEDOT:PSS films10.1016/j.orgel.2013.12.023 ↗
40. Ultrahigh Thermoelectric Properties of PEDOT:PSS Films by Dedoping and π-π Overlapping With 4-(1,3-dimethyl-2,3-dihydro-1H-benzoimidazol-2-yl)phenyl)Dimethylamine (N-DMBI)10.1002/adfm.202506872 ↗
41. Enhanced thermoelectric performance of PEDOT:PSS film by two-step post-treatment with mixed solvent based ionic liquid10.1016/j.orgel.2025.107289 ↗
42. Enhanced thermoelectric performance of PEDOT:PSS/SWCNT/PDDA three-component composite films10.1039/D5RA08134C ↗
43. Enhancement of thermoelectric performance of PEDOT:PSS films by post-treatment with a superacid10.1039/C8RA02058B ↗
44. Enhanced high temperature thermoelectric response of sulphuric acid treated conducting polymer thin films10.1039/C5TC03145A ↗
45. Simultaneous improvement in electrical conductivity and Seebeck coefficient of PEDOT:PSS by N 2 pressure-induced nitric acid treatment10.1039/C8RA06094K ↗
46. PEDOT/PSS: synthesis, characterization, properties and applications10.1016/S0379-6779(02)00518-0 ↗
47. Synthesis and polymerization of polyelectrolyte-based conductive inks: the protagonism of the coadjutant oxidizing salt10.1039/D4PY00574K ↗
48. Tunable Charge-Density PEDOT:PSS for Application in Post-Synaptic Organic Neuromorphic Electrodes
49. Enhancement of the thermoelectric properties of PEDOT:PSS thin films by post-treatment10.1039/c3ta11209h ↗
50. Organic electrochemical transistors10.1038/natrevmats.2017.86 ↗
51. On the transient response of organic electrochemical transistors10.1016/j.orgel.2017.03.021 ↗
52. Steady-State and Transient Behavior of Organic Electrochemical Transistors10.1002/adfm.200601239 ↗
53. Functional Sensing Interfaces of PEDOT:PSS Organic Electrochemical Transistors for Chemical and Biological Sensors: A Mini Review10.3390/s19020218 ↗
54. Organic Electrochemical Transistors (OECTs) Toward Flexible and Wearable Bioelectronics10.3390/molecules25225288 ↗
55. The structure and properties of PEDOT synthesized by template-free solution method10.1186/1556-276X-9-557 ↗
56. Fundamentos da síntese de tintas condutivas de PEDOT:PSS: como fenômenos moleculares, conformacionais e eletrostáticos ditam propriedades optoeletrônicas de filmes no estado sólido
57. High work function with reduced phase separation of PSS in metal oxide modified PEDOT:PSS interlayers for organic photovoltaics10.1039/C6RA23170E ↗
58. Highly conductive PEDOT:PSS treated by sodium dodecyl sulfate for stretchable fabric heaters10.1039/C6RA24749K ↗
59. Improvement of the thermoelectric properties of PEDOT:PSS films via DMSO addition and DMSO/salt post-treatment resolved from a fundamental view10.1016/j.cej.2021.132295 ↗
60. A Novel and Green Method for Preparing Highly Conductive PEDOT:PSS Films for Thermoelectric Energy Harvesting10.3390/polym16020266 ↗
61. The effect of oxygen on the efficiency of planar p–i–n metal halide perovskite solar cells with a PEDOT:PSS hole transport layer10.1039/C7TA11128B ↗
62. Nanostructural Modification of PEDOT:PSS for High Charge Carrier Collection in Hybrid Frontal Interface of Solar Cells10.3390/polym11061034 ↗
63. Vibrational signatures of electrochemical p- and n-doping of poly(3,4-ethylenedioxythiophene) films: an in situ attenuated total reflection Fourier transform infrared (ATR-FTIR) study10.1016/S0022-2860(99)00442-1 ↗
64. Douglas A.Skoog, F. James Holler, Stanley R.Crouch, Principles of Instrumental Analysis, 7th ed., Boston, 2016.
65. UV-to-IR Absorption of Molecularly p-Doped Polythiophenes with Alkyl and Oligoether Side Chains: Experiment and Interpretation Based on Density Functional Theory10.1021/acs.jpcb.0c08757 ↗
66. Higher PEDOT Molecular Weight Giving Rise to Higher Thermoelectric Property of PEDOT:PSS: A Comparative Study of Clevios P and Clevios PH100010.1021/acsami.6b15158 ↗
67. How does PEDOT combine with PSS? Insights from structural studies10.1039/C4RA08666J ↗
68. Structural control of mixed ionic and electronic transport in conducting polymers10.1038/ncomms11287 ↗