15-Fold increase in solar thermoelectric generator performance through femtosecond-laser spectral engineering and thermal management.

Solar thermoelectric generators (STEGs) have recently gained increasing attention. However, their widespread adoption has been limited due to the lack of high-efficiency thermoelectric materials and compact heat sinks for effective heat dissipation. To address these issues, we develop a spectral engineering and thermal management strategy that significantly increases STEG power generation by 15 times with only a 25% increase in weight. At the hot side, we transform a regular tungsten (W) to a selective solar absorber (W-SSA) through a femtosecond (fs)-laser processing technique, which enhances the solar absorption while minimizing the IR emissivity, obtaining >80% absorption efficiency at elevated temperatures. We also design a greenhouse chamber for W-SSA and achieved >40% reduction in convective heat loss. At the cold side, we apply the fs laser processing to transform a regular aluminum (Al) to a super-high-capacity micro-structured heat dissipator (μ-dissipator), which improves the cold-side heat dissipation through both radiation and convection, achieving twice the cooling performance of a regular Al heat dissipator. These spectral engineering and thermal management increase the temperature difference across the STEG, resulting in a substantial increase in output power. The high-efficiency STEG can find a wide range of applications, such as wireless sensor networks, wearable electronics, and medical sensors.