Nano‐ITO Induced Janus Membrane Enables Spectrally Selective Photothermal Compensation for Passive Daytime Thermal Management

Abstract Passive daytime radiative cooling (PDRC), as a core technology of passive daytime thermal management (PDTM), offers broad applicability for thermal/radiative protection of the internal environment without energy consumption. For the indispensable polymer matrix or polymer adhesive in PDTM materials, an appropriate working environment of a cooling–heating balance is crucial. However, the lack of core PDTM material with selective photothermal characteristics results in the inability to achieve a cooling–heating balance during non‐cooling seasons. After verifying the unique characteristics of nanostructured ITO with the collective oscillation frequency of free electrons to couple with low‐frequency light, a spectrally selective photothermal compensation strategy is designed combining wide bandgap absorbance (UV) and localized surface plasmon resonance effect (NIR) to develop a Janus membrane with nano‐ITO as the selective photothermal absorber. In heating mode, its particular selective photothermal compensation contributes to the environmental temperature enhancement of less than 0.5 °C. Upon cooling mode, an 8.1 °C reduction is also maintained. This strategy achieves a good balance between cooling and heating on the basis of obtaining a higher cooling level. The establishment of zero energy‐consumption PDTM technology with a superior cooling‐heating trade‐off can satisfy the urgent need to support the sustainable development of a comfortable society.