Multilayer film for adaptive emissivity modulation

Smart thermal radiation regulation with emissivity modulation properties is one of the important approaches in thermal management, which has attracted extensive attention in saving energy consumption in buildings. The temperature-adaptive emissivity modulation is an interesting topic in thermal radiation management since it changes the material’s emissivity according to the surface temperature and controls its thermal properties, behaving like a thermostat. Vanadium dioxide (VO2) is a classical temperature-adaptive phase-change material that reversibly transitions between the insulating phase at low temperatures and the metallic phase at high temperatures, accompanied by changes in optical parameters. In this work, we have designed a high solar absorptive with dynamic emissivity device based on VO2 coating to achieve energy efficiency in buildings. The structure can achieve an absorptivity of more than 0.7 in the solar radiation band, and an emissivity modulation of 0.65 in the “atmospheric window”. We simulated building energy consumption in 11 cities in northern China. For example, in Beijing, building consumption can save 24.7 GJ and 16 GJ of annual energy consumption compared to buildings using white paint and blue titanium materials, respectively. Additionally, the distribution of electric fields and normalized power density are investigated, and it is found that the absorption enhancement originates from the inherent loss of the medium coupled with multilayer effect. In summary, our work provides a solution for adaptive emissivity modulation, which can be applied in various areas, including intelligent temperature control for spacecraft and building thermal management.