Figure: Construction strategy of N-type thermoelectric rubber

Supported by the National Natural Science Foundation of China (Grant Nos.: T2425010, 52303216, 52403219, T2441002) and other funding sources, a research team led by Professor Ting Lei from Peking University, with their collaborators, has proposed the novel concept and molecular design strategy of "thermoelectric rubber", providing a new approach to addressing the long-standing challenge in the field of thermoelectric materials—balancing mechanical, electrical, and thermal properties. This study, titled "N-type thermoelectric elastomers", was published in Nature on August 13, 2025 (https://www.nature.com/articles/s41586-025-09387-z).

With the rapid development of wearable electronics and bioelectronics, the development of flexible wearable energy supply systems that combine high-efficiency energy conversion, sustained power output, and perfect conformability has become a critical bottleneck. Although traditional inorganic thermoelectric materials have exhibited excellent thermoelectric performance, their intrinsic brittleness and lack of stretchability impose two fundamental limitations: (1) inability to adapt to dynamic deformation on curved human body surfaces, and (2) susceptibility to performance degradation under repeated strain.

To overcome these challenges, Professor Lei’s team introduced the concept of "thermoelectric elastomers" or "thermoelectric rubber" and realized this new type of material through three innovative strategies:

1. Nanophase Separation Control: By constructing a uniformly distributed semiconducting polymer nanofiber network, the team significantly enhances charge carrier mobility.

2. Thermally Activatable Crosslinking: Introducing a diazirine-based crosslinker endows the material with ultrahigh stretchability (>850%) while maintaining over 90% elastic recovery at 150% strain, comparable to conventional rubber.

3. Targeted Doping: By selecting appropriate dopants, efficient doping of semiconducting nanofibers can be realized, simultaneously improving electrical conductivity and Seebeck coefficient, along with a unique strain-induced conductivity enhancement.

Moreover, the team discovered that blending structures—where insulating rubber coats the semiconducting nanofibers—can enhance interfacial phonon scattering, significantly reducing thermal conductivity. As a result, both the mechanical and thermoelectric properties of the material are greatly improved. The n-type thermoelectric material achieved a thermoelectric figure of merit (ZT) of 0.49 at 300 K, rivaling or even surpassing existing flexible/ductile inorganic thermoelectric materials.

Based on this breakthrough, the team developed the first elastic thermoelectric generator module that adheres tightly to human skin during motion, enabling continuous harvesting and conversion of body heat. This innovation holds promise for powering low-power-consumption wearable electronics and biosensors.