Spaceborne power systems must operate reliably for decades with minimal maintenance. Thermoelectric generators (TEGs) are intrinsically suited to long-lived missions, but their output remains constrained by available thermal gradients and the limitations of bulk thermoelectric materials. Here, we introduce a photonic metamaterial (PtMM) coating concept that amplifies the thermal gradient available to a TEG by converting incident AM0 solar irradiance into strongly localised photothermal energy on the TEG hot side. We design, optimise, and numerically characterise two metal-insulator-metal PtMM geometries – nanocross (NC-PtMM) and nanosquare (NS-PtMM) – using standard thin-film materials.
