Switchable Narrowband Diffuse Thermal Emission With an In3SbTe2-Based Planar Structure

Tailoring of thermal radiation is critical for applications like daytime radiative cooling, thermophotovoltaic energy conversion, and gas sensing. Phase-change materials (PCMs) offer an additional degree of freedom, enabling reconfigurable thermal emission by actively triggering phase transitions. In particular, In<inf>3</inf>SbTe<inf>2</inf> (IST) features a unique non-volatile phase transition in the infrared between an amorphous dielectric state and a crystalline metallic state. Although efficient and easily manufacturable alternatives to conventional infrared light sources will be highly desirable, achieving narrowband and diffuse emission using a simple, lithography-free structure incorporating PCMs for dynamic functionalities has remained elusive. Here, a planar reconfigurable narrowband thermal emitter using an IST layer on top of a Salisbury screen is demonstrated. The design achieves high emissivity around the ambient thermal wavelength in the amorphous phase and low emissivity in the crystalline phase, featuring angle- and polarization-independent behavior. Multiple patterns are optically written into the IST layer, demonstrating centimeter-scale programmability as well as a resolution of 20 µm. This work paves the way toward reconfigurable and easily manufacturable devices, showing potential for applications in labeling and anticounterfeiting.