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Harvesting waste heat with flexible Bi2Te3 thermoelectric thin film

Abstract

Thermoelectric materials offer the possibility of harvesting huge amounts of waste heat, such as vehicle exhaust gases, and converting them directly into useful electricity, a process that generates power more sustainably. Flexible thermoelectrics have emerged as a technology to power wearable electronics and sensors, although coupling of thermoelectric performance and flexibility remains a big challenge. Here, we show a Bi2Te3 thin-film design that features high thermoelectric performance (room-temperature figure of merit ZT of ~1.2) and high flexibility (surviving 2,000 bending tests at an 8 mm bending radius). The favourable combination of high performance and flexibility is rooted in the textured structure of the film on the (00l) plane. The assembled flexible device from 40 pairs of thin films exhibits an outstanding output power density of 2.1 mW cm−2 at a temperature gradient of 64 K, demonstrating potential application in harvesting thermal energy from the environment or human bodies.

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Fig. 1: Ag-doped Bi2Te3 thermoelectric thin film and prototype device with outstanding thermoelectric performance and flexibility.
Fig. 2: Microstructural and nanostructural characterization of 1.33% Ag-doped Bi2Te3 thin film and calculated formation energy of different point defects.
Fig. 3: Thermoelectric properties and calculated band structures of Bi2Te3 thin films with different Ag-doping concentrations.
Fig. 4: Thermal transport properties, ZTs and flexibility of Bi2Te3 thin films with different Ag contents.
Fig. 5: Performance of thin-film-based thermoelectric devices.

Data availability

The data that support the findings detailed in this study are available in the article and its Supplementary Information or from the corresponding authors upon reasonable request. Source data are provided with this paper.

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Acknowledgements

This work was supported by the National Natural Science Foundation of China (62274112 and 11604212), the National Natural Science Foundation of Guangdong province of China (2022A1515010929) and the Science and Technology Plan Project of Shenzhen (JCYJ20220531103601003 and 20200811230408001). Z.G.C. acknowledges the financial support provided by the Australian Research Council, the QUT capacity building programme and Innovation Centre for Sustainable Steel Project. The authors are thankful for the assistance on STEM HAADF observation received from the Electron Microscope Center of Shenzhen University.

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Z.G.C. and P.F. supervised the project and conceived the idea. Z.H.Z., X.L.S., D.W.A., G.Q.L. and Z.G.C. designed the experiment and wrote the manuscript. Z.H.Z. and D.W.A. synthesized the materials. X.L.S., W.D.L., F.L. and G.X.L. performed the thermoelectric performance evaluation. D.W.A., Y.X.C. and M.W. characterized the materials. M.L., L.Z.K. and W.D.L. undertook the theoretical work. All the authors discussed the results and commented on the manuscript. They have approved the final version of the manuscript.

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Correspondence to Ping Fan or Zhi-Gang Chen.

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Nature Sustainability thanks Kefeng Cai and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary information

Supplementary Information

Supplementary Figs. 1–27 and Tables 1–6.

Supplementary Video 1

Flexibility test of the thin film.

Supplementary Video 2

Flexibility test of the prototype device.

Supplementary Video 3

Stable output voltage by wearing the F-TEG.

Supplementary Video 4

F-TEG acts as a switch to light the LED.

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Zheng, ZH., Shi, XL., Ao, DW. et al. Harvesting waste heat with flexible Bi2Te3 thermoelectric thin film. Nat Sustain (2022). https://doi.org/10.1038/s41893-022-01003-6

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