All-Nitride Fabry–Pérot Absorbers with Exceptional Flexibility and Thermal Stability

Flexible photonic absorbers with exceptional thermal stability are essential for flexible nonlinear, thermophotovoltaic, and photothermal conversion applications, which are currently difficult to achieve due to the vulnerability of many materials (e.g., noble metals) and organic substrates to high temperatures and intensive light illumination. Here, flexible yet refractory photonic absorbers made of single-crystalline TiN/ScN/TiN Fabry-Pérot (FP) cavities have been created on flexible fluorophlogopite mica (F-mica) substrates by a magnetron sputtering epitaxy system. Thanks to the high refractive index of ScN cavity layers, these flexible all-nitride FP absorbers are compact and show excellent omnidirectional light absorption. Notably, their near-complete light absorption remains very stable after 1000 bending cycles and high-temperature heat treatments. The thermal stability at 1000 °C in vacuum and 500 °C in air shown by these all-nitride FP absorbers significantly surpasses the typical working temperature (around 200 °C) for conventional flexible photonic absorbers. This work provides a simple, scalable, and promising approach to fabricating flexible and compact photonic absorbers with outstanding thermal stability, making them highly suitable for various flexible but refractory nanophotonic and photothermal applications.