Interphase-Driven Suppression of Thermal Conductivity in Multilayered Thermoelectric Polymer Heterojunctions

作者：Chunlin Xu, Dongyang Wang, Dongyang Wang, Chong‐an Di, Dong Wang, Dong Wang · 发表于：Macromolecules · 年份：2026 · DOI：10.1021/acs.macromol.5c02503 · 研究领域：Advanced Thermoelectric Materials and Devices、Thermal properties of materials、Organic Electronics and Photovoltaics

Multilayered heterojunctions of thermoelectric polymers, which comprise alternating nanoscale semicrystalline polymer layers and interphases, exhibit markedly suppressed thermal conductivity. However, the origin of this suppression and its correlation with the heterojunction structure remain unclear, primarily due to limited understanding of the interphase. Here, we integrate molecular dynamics simulations, thermal transport models, and experimental characterization to investigate a model heterojunction system consisting of selenium-substituted diketopyrrolopyrrole (PDPPSe) and poly(2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2- b ]thiophene) (PBTTT). We reveal an ultralow thermal conductivity (∼0.034 W m –1 K –1 ) in the 4 nm thick interphases of this system, which arises from their amorphous and porous morphology. This finding identifies two primary contributors to the overall in-plane thermal conductivity suppression in polymer multilayered heterojunctions: (1) the ultralow thermal conductivity of the interphases, and (2) conventional diffuse phonon scattering at rough interfaces. Although both effects exhibit strong dependence on layer thickness, interphase thermal resistance dominates once the interphase thickness approaches that of the semicrystalline polymer layers. This work establishes the pivotal role of interphase thermal transport in layered polymer architectures and highlights interphase engineering as a promising strategy for tuning thermal conductivity.