Microstructured surfaces for colored and non-colored sky radiative cooling.

We propose a simple structure for passive sky radiative cooling made of a surface-textured layer of silica on a silver substrate. Using electromagnetic simulations, we show that the optical properties of such structures are near-ideal, due to the large reflectivity of silver in the solar spectrum and the large emissivity of silica in the infrared. Surface texturation is key to obtain near-unity emissivity in the infrared.

New insights into the thermal behavior and management of thermophotovoltaic systems.

The thermal behavior of a thermophotovoltaic system composed of a metallo-dielectric spectrally selective radiator at high temperature and a GaSb photovoltaic cell in the far field is investigated. Using a coupled radiative, electrical and thermal model, we highlight that, without a large conductive-convective heat transfer coefficient applied to the cell, the rise in temperature of the photovoltaic cell induces dramatic efficiency losses. We then investigate solutions to mitigate thermal effects, such as radiative cooling or the decrease of the emissivity or the temperature of the radiator.

Radiative Thermal Memristor.

Based on the thermal hysteresis of a phase change material exchanging radiative heat with a phase invariable one, we propose a radiative thermal memristor characterized by a Lissajous curve between their exchanged heat flux and temperature difference periodically modulated in time. For a memristor with terminals of VO_{2} and a blackbody, it is shown that (i) the temperature variations of its memristance follow a closed loop determined by the thermal hysteresis width of VO_{2}, and (ii) the thermal memristance on-off ratio is determined by the contrast of VO_{2} emissivities for its insulating and metallic phases and is equal to 3.6.

Polaritonic figure of merit of plane structures.

Based on the ability of plane structures to simultaneously optimize the propagation, confinement, and energy of surface plasmon-polaritons or surface phonon-polaritons, we develop the polaritonic figure of merit Z = βRΛ/δ, where βR, Λ and δ are the longitudinal wave vector, propagation length, and penetration depth, respectively. Explicit and analytical expressions of Z are derived for a single interface and a suspended thin film, as functions of the material permittivities and the film thickness. Higher Z are obtained for thinner films and smaller energy losses.

Quantum Thermal Transistor.

We demonstrate that a thermal transistor can be made up with a quantum system of three interacting subsystems, coupled to a thermal reservoir each. This thermal transistor is analogous to an electronic bipolar one with the ability to control the thermal currents at the collector and at the emitter with the imposed thermal current at the base. This is achieved by determining the heat fluxes by means of the strong-coupling formalism.

Radiative thermal rectification between SiC and SiO2.

By means of fluctuational electrodynamics, we calculate radiative heat flux between two planar materials respectively made of SiC and SiO2. More specifically, we focus on a first (direct) situation where one of the two materials (for example SiC) is at ambient temperature whereas the second material is at a higher one, then we study a second (reverse) situation where the material temperatures are inverted. When the two fluxes corresponding to the two situations are different, the materials are said to exhibit thermal rectification, a property with potential applications in thermal regulation.