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Dual‐Spectral Design of Porous Anodic Alumina for Tunable Colored Passive Radiative Cooling

ملخص البحث

Passive radiative cooling requires materials that combine high mid-infrared (MIR) emissivity within the atmospheric transparency window (8–13 µm) with minimal solar absorption, while maintaining scalability and long-term stability. Porous anodic alumina (PAA) is an attractive dielectric platform due to its intrinsic phonon-polariton infrared emission and electrochemically tunable nanostructure. However, achieving independent control of visible photonic properties and MIR emissivity within a single architecture remains challenging. Here, we demonstrate dual-spectral control of PAA photonic structures integrated with aluminum (Al) substrates using charge density-controlled sinusoidal pulse anodization. Periodic voltage modulation generates well-defined photonic stop bands (PSBs) in the visible range, enabling tunable structural coloration while preserving high MIR emissivity. Systematic pore widening produces a progressive blue shift of the PSB accompanied by non-monotonic reflectance changes, revealing distinct mechanisms governing spectral position and optical coherence. In contrast, MIR emissivity remains robust against variations in the visible photonic response, as confirmed by a constant-voltage reference sample. The PAA architecture provides intrinsic optical impedance matching through a gradual refractive-index transition, while the Al substrate acts independently as a back reflector that suppresses transmission losses. These findings establish PAA as a versatile platform for color-designed radiative cooling surfaces with independently engineered optical and thermal functionalities.

مؤلف البحث
Zeinelabedin A. Mohamed, Maksymilian Włodarski, Małgorzata Norek
تاريخ البحث
قسم البحث
مجلة البحث
Small
مؤلف البحث
سنة البحث
2026