Abstract
The control of heat transport in organic materials has attracted increasing attention for developing thermal transistors and other heat-regulating devices. Here, we demonstrate continuous and reversible modulation of the thermal conductivity (\({\kappa }_{\perp }\)) of polymer poly[2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophene] (PBTTT) films along the lamellar-stacking (out-of-plane) direction via electrochemical doping. \({\kappa }_{\perp }\) values were quantitatively evaluated under gating conditions using a gold-based time-domain thermoreflectance system. Upon electrochemical doping, \({\kappa }_{\perp }\) increased by 28%, from 0.198 to 0.253 W m−1 K−1, and the modulation of the thermal conductivity by the shift of gate voltage is achieved. Atomistic simulations revealed how molecular intercalation and the associated changes in local structural conformation affect spectral thermal transport in the host PBTTT matrix, providing insight into the mechanism behind the increased \({\kappa }_{\perp }\). These results confirm that electrochemical doping enables reversible and controllable tuning of thermal conductivity, a key requirement for thermal management applications, paving the way for future advancements in thermally tunable organic materials.
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The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.
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Acknowledgements
We thank Dr. K. Adachi of the RIKEN Center for Emergent Matter Science, Materials Characterization Support Team, for his support with the X-ray diffraction experiments. K.Y. acknowledges support from Grant Nos. JP20H02573, JP21H05017, JP22H05469, JP23H00259, JP24H01200 and JPJSBP120252302, and JST CREST through Grant No. JPMJCR17I5 and JPMJCR2544, Japan. K.Y. acknowledges US-JAPAN PIRE collaboration, Grant No. JPJSJRP20221202, Japan and ASPIRE project, Grant No. JPMJAP2310, Japan. K.U. acknowledges support from JSPS KAKENHI (JP24K07342). T.S. acknowledges the support from JST FOREST through Grant No. JPMJFR222G, Japan. S.S. acknowledges the support from JST SPRING, Grant Number JPMJSP2156. S.I. acknowledges the support from Grant-in-Aid for JSPS Fellows No. 24KJ1260. T.T. acknowledges support from JST CREST, Grant No. JPMJCR23A4. Finally, the authors thank Mr. Benjamin Hillam for his support in checking and reviewing the manuscript.
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S.I., K.U., and K.Y. conceived the idea. K.Y. and T.T. supervised the project. S.I., K.U., and S.S. fabricated the device and contributed to the measurement. K.U. and T.Y. analyzed thermal properties based on TDTR data. S.S. and T.S. calculated the heat transport across modeled polymer structures. S.I., K.U., T.S., S.K., T.Y., S.W., T.T, and K.Y. contributed to the discussion. All authors contributed to the review of the manuscript.
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Communications Materials thanks Ioannis Petsagkourakis, Mariano Campoy and the other anonymous reviewer(s) for their contribution to the peer review of this work. A peer review file is available.
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Ito, Si., Ueji, K., Saito, S. et al. Modulation of heat flow via electrochemical doping in conducting polymer PBTTT. Commun Mater (2026). https://doi.org/10.1038/s43246-026-01151-8
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DOI: https://doi.org/10.1038/s43246-026-01151-8
