High-performance dynamic thermal emitter based on Fabry−Pérot surface cavity comprising multi-phase VO2 layer

• Published in: International journal of thermal sciences Vol. 215; p. 109960
• Main Authors: Kim, Jaehyeong, Kang, Dongkyun, Lee, Eun-Joo, Kim, Sun-Kyung, Lee, Myeongkyu
• Format: Journal Article
• Language: English
• Published: Elsevier Masson SAS 01.09.2025
• Subjects: Dynamic thermal emitter; Fabry−Pérot cavity; Temperature-adaptive emissivity modulation; VO2 film; Fabry−Pérot cavity; Temperature-adaptive emissivity modulation; VO2 film; Dynamic thermal emitter
• ISSN: 1290-0729
• DOI: 10.1016/j.ijthermalsci.2025.109960

The dynamic control of thermal emission is applicable to various fields, including personal thermal management, energy-saving buildings, and camouflage. VO2 is promising for this purpose because M1-phase VO2 undergoes a reversible phase transition between insulating and metallic states at ∼68 °C, and its optical constants at mid-infrared wavelengths significantly differ in these two states. However, the thermodynamically narrow window and polymorphic nature of VO2 render it extremely challenging to grow pure M1-phase VO2 films. Herein, we investigate temperature-adaptive emissivity regulation with a Fabry−Pérot cavity comprising VO2/ZnS/Al layers formed on a glass substrate and demonstrate that considerable emissivity modulation can be achieved even when the VO2 layer is not of the pure M1-phase and contains other phases. An experimental emissivity modulation of 0.47 is obtained between 20 °C and 60 °C with an ordinary multi-phase VO2 layer, which exhibits a resistivity change of 2.6 orders of magnitude. Another important finding in this study is that when the thickness of the VO2 layer exceeds 60 nm, the emissivity is maximized before the layer is completely transformed into the metallic state. This feature, as demonstrated both experimentally and numerically, is encouraging because it can reduce the operating temperature of the emitter significantly. [Display omitted] •A surface cavity structure comprising VO2/ZnS/Al layers is presented as a dynamically tunable thermal emitter.•An experimental emissivity modulation of 0.47 is obtained between 20 °C and 60 °C with an ordinary multi-phase VO2 layer.•The emissivity of the cavity is maximized before the VO2 layer is completely transformed into the metallic state.