High Efficiency Breathable Thermoelectric Skin Using Multimode Radiative Cooling/Solar Heating Assisted Large Thermal Gradient

Yeongju Jung; Seongmin Jeong; Jiyong Ahn; Jinwoo Lee; Seung Hwan Ko

doi:10.1002/smll.202304338

High Efficiency Breathable Thermoelectric Skin Using Multimode Radiative Cooling/Solar Heating Assisted Large Thermal Gradient

Small. 2024 Jan;20(1):e2304338. doi: 10.1002/smll.202304338. Epub 2023 Aug 30.

Authors

Yeongju Jung¹, Seongmin Jeong¹, Jiyong Ahn¹, Jinwoo Lee², Seung Hwan Ko^{1

3

4}

Affiliations

¹ Applied Nano and Thermal Science Lab, Department of Mechanical Engineering, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, Republic of Korea.
² Department of Mechanical, Robotics, and Energy Engineering, Dongguk University, 30 Pildong-ro 1-gil, Jung-gu, Seoul, 04620, Republic of Korea.
³ Institute of Advanced Machinery and Design (SNU-IAMD), Seoul National University, Gwanak-ro, Gwanak-gu, Seoul, 08826, Republic of Korea.
⁴ Institute of Engineering Research, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul, 08826, Republic of Korea.

PMID: 37649174
DOI: 10.1002/smll.202304338

Abstract

This study proposes a Janus structure-based stretchable and breathable thermoelectric skin with radiative cooling (RC) and solar heating (SH) functionalities for sustainable energy harvesting. The challenge of the wearable thermoelectric generator arises from the small temperature difference. Thus, this dual-sided structure maximizes the thermal gradient between the body and the surrounding environment, unlike the previous works that rather concentrate on the efficiency of the thermoelectric generator itself. The Janus structure allows the device to switch to the other mode, optimizing electricity generation from a given weather condition. For these functionalities, for the first time, boron nitride-polydimethylsiloxane (BP) and graphene nanoplatelet-polydimethylsiloxane (GP) nanofiber (NF) are developed as substrates. The BP NF generates the RC capability of ΔT_cooling = 4 °C, and the high solar absorbance of the GP NF enables it to be photothermally heated. The flip-overable thermoelectric skin (FoTES) achieves a maximum power output (P_max ) of 5.73 µW cm^-2 in RC mode, surpassing SH mode by 5.55 µW cm^-2 in the morning. In the afternoon, it generates a P_max of 18.59 µW cm^-2 in SH mode, outperforming RC mode by 15.56 µW cm^-2 . This work contributes to the advancement of wearable electronics, offering a sustainable power source in a wearable form.

Keywords: breathable electronics; electrospun fiber electronics; radiative cooling; solar heating; sustainable energy harvesting; thermoelectric skin.