Thermal Emission Modulation by Electron Population in Quantum Dots

We report an efficient temperature modulation of thermal emissivity near room temperature using quantum dots. The quantum confinement effects result in a unique feature that resembles a quasi-two-level electronic system (QTLES). The QTLES's dielectric function ϵ(ω) is shown to be dependent on the electron population difference δρ(T), which exhibits strong temperature dependence and can be tuned by adjusting the Fermi-level of the solid. Experiments with the Ag_{2}Se quantum dots confirm the theory and showcase a modulate rate dε/dT≈1.5×10^{-3} K^{-1} that meets the requirements for engineering applications. This study demonstrates an exciting new avenue for temperature modulation of thermal emission and may open up new possibilities for applications like energy harvesting, thermal camouflage, thermal rectifications, and many others.