An all-in-one Ag<sub>2</sub>Se-based flexible solar-thermoelectric generator with photothermal integration.

Hou, Shuaihang; Wang, Jian; Zhang, Guixia; Liu, Xinqi; Wu, Zuoxu; Liu, Bingshang; Lu, Mengyang; Zhang, Muhao et al. · Nat Commun · 2026

basic_science · Level V

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Abstract

Flexible solar-thermoelectric generators hold great promise for efficient solar energy harvesting and power supply in wearable electronics. However, the achievement of strong photothermal and thermoelectric performance simultaneously within a single material remains a significant challenge. Here, we propose a fully integrated solar-thermoelectric generator that directly employs Ag<sub>2</sub>Se thermoelectric thin films as the light-absorbing terminal, combined with a bottom infrared-reflective layer and surface visible anti-reflective coating. This multilayer architecture enables solar-selective absorption and enhances the photothermal conversion efficiency of Ag<sub>2</sub>Se up to 87.6%, while demonstrating good generalizability to other narrow-bandgap thermoelectric films. The resulting ring-shaped flexible generator delivers a maximum temperature difference and power density of 19.6 K and 0.17 μW cm<sup>-2</sup> under 1-sun irradiation and exhibits a stable peak output power of ~1 μW under prolonged outdoor sunlight. These results highlight an effective strategy for high-efficiency solar-thermoelectric generators design and broaden the application potential of narrow-bandgap thermoelectric thin films in photothermal energy conversion.