Hybrid photothermal structure based on Cr-MgF₂ solar absorber/PMMA-graphene heat reservoir for enhanced thermoelectric power generation

In this paper, a facile strategy for a hybrid photothermal structure that can efficiently manage solar heat is reported. The hybrid photothermal structure consists of a Cr/MgF₂ multilayer structure absorber and a poly(methyl methacrylate) (PMMA)-graphene heat reservoir that prevents the absorbed heat from being lost through radiation or convection. It exhibits a quite high light absorption of approximately 80% over a wavelength range of 0.5–2.5 µm. The thermal conductivity and thermal diffusivity are improved by about 47% according to the addition of graphene to PMMA, effectively transferring the stored heat to a place where it can be used efficiently. When the hybrid photothermal structure was applied to the hot zone of a thermoelectric generator, the output voltage is improved by 2.74 times compared to the device with only the light absorber. In addition, the difference between the high and low temperatures reached up to approximately 27 K.