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Wearable thermoelectric generators (WTEGs) have relied on soft encapsulation materials typically used for the structural support of thermoelectric legs. Heat loss through the filler and low heat transfer via the mismatched contact with the skin causes a small temperature gradient between the human body (hot side) and the natural environment (cold side). Instead of using soft encapsulation materials, a partially air‐filled deformable gasket is purposed for leg support, achieving the thermal isolation of thermoelectric legs by preventing parasitic heat transfer. The WTEG comprising the deformable gasket exhibits a 30% larger temperature gradient than that with conventional encapsulant structures filled with soft materials. Additionally, the deformable gasket shows an auxetic metastructure owing to its negative Poisson's ratio, reversibly responding to changes in their environment, which is suitable for skin‐like stretchable wearable devices. The band type of WTEG with the optimized leg geometry and fill factor shows a power output of 2 uW cm−2 for eight pairs of thermocouples, a record‐high value among the stretchable TEGs obtained indoors at room temperature (23 °C) without wind. This approach paves the way for the efficient conversion of thermal energy into electrical energy and broadens potential applications for self‐powered wearable electronics. [ABSTRACT FROM AUTHOR]

For a policy of 100% renewable energy, most renewable‐energy research is aimed at decarbonization; particular emphasis is being placed on increasing the portion of electricity generated by photovoltaics (PVs). As the application fields of PVs broadens from PV power plants and rooftop to various urban environments, achieving high energy yields requires expansion beyond current PV module structures. To satisfy these demands, honeycomb‐structured PV modules with incorporated mechanical metamaterials are proposed, to overcome the aforementioned problems associated with the limited mechanical properties of PVs, and to advance the development of 3D PV modules with enhanced energy yield. The honeycomb structures provide 28% greater power compared with flat cells by utilizing extra reflected or scattered light inside a 3D tetrahedron structure. For mechanical robustness, the 3D concave tetrahedron units are supported by a 3D‐structured mechanical metamaterial that exhibits a negative Poisson's ratio and is arranged in a 3D pattern. [ABSTRACT FROM AUTHOR]