Trimode Integrated Solar-Thermal Stacked Converters for Sustainable Active Buildings

High-efficiency solar-thermal conversion has received widespread attention in seawater desalination, purification, catalysis, and power generation. However, challenges still exist in the exploitation of the solar-thermal converters capable of thermal concentration to simultaneously suppress serious heat loss from conduction, convection, and radiation, which always leads to photothermal temperature <70 °C under 1-sun illumination. Herein, a solar-thermal converter integrated with trimode thermal concentration capabilities is prepared by in situ deposition of three stacked function layers (crumpled light-absorbing microtexture, transparent insulating silica aerogel, and transparent low-emission micronetwork) to simultaneously guarantee solar energy transmission/conversion and prevent conduction, convection, and radiation loss. As a result, the trimode integrated solar-thermal converter shows equilibrium temperatures as high as 90.9 °C under 1-sun illumination and 174 °C under 3-sun illumination, which is higher than most previously reported converters. Finally, a sustainable active building model is built with a power-generation roof to efficiently utilize solar-thermal energy. The solar-thermal converters synchronously drive constant thermoelectric generation (4.6 V, P_max = 0.85 W m^–2) and water heating (from 15.9 to 31.3 °C). The generated voltage powers smart electrochromic windows with the transmission modulation of natural light and its heat gain, significantly increasing indoor living comfort and saving energy in buildings by reducing lighting, heating, ventilation, and cooling loads.