Multi-heterojunctioned plastics with high thermoelectric figure of merit.

Wang, Dongyang; Ding, Jiamin; Ma, Yingqiao; Xu, Chunlin; Li, Zhiyi; Zhang, Xiao; Zhao, Yao; Zhao, Yue et al. · Nature · 2024

basic_science · Level V

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Abstract

Conjugated polymers promise inherently flexible and low-cost thermoelectrics for powering the Internet of Things from waste heat<sup>1,2</sup>. Their valuable applications, however, have been hitherto hindered by the low dimensionless figure of merit (ZT)<sup>3-6</sup>. Here we report high-ZT thermoelectric plastics, which were achieved by creating a polymeric multi-heterojunction with periodic dual-heterojunction features, where each period is composed of two polymers with a sub-ten-nanometre layered heterojunction structure and an interpenetrating bulk-heterojunction interface. This geometry produces significantly enhanced interfacial phonon-like scattering while maintaining efficient charge transport. We observed a significant suppression of thermal conductivity by over 60 per cent and an enhanced power factor when compared with individual polymers, resulting in a ZT of up to 1.28 at 368 kelvin. This polymeric thermoelectric performance surpasses that of commercial thermoelectric materials and existing flexible thermoelectric candidates. Importantly, we demonstrated the compatibility of the polymeric multi-heterojunction structure with solution coating techniques for satisfying the demand for large-area plastic thermoelectrics, which paves the way for polymeric multi-heterojunctions towards cost-effective wearable thermoelectric technologies.