Condensation of cavity exciton-polaritons in perovskite nanocrystals at room-temperature

Strong light–matter coupling and exciton-polariton condensates have emerged as powerful means of integrating interactions and nonlinearities into a wide array of photonic systems, from low-threshold topological lasers to ultrafast all-optical logic circuits. Colloidal semiconductor quantum dots, featuring strong three-dimensional confinement, offer a particularly appealing active medium for such microcavities due to their tunable structural and compositional properties, straightforward wet-chemical synthesis, and potentially enhanced polaritonic interactions arising from confinement. However, cavity exciton-polariton condensation has not yet been reported in epitaxial or colloidal quantum dots. In this work [1], we demonstrate room-temperature polariton condensation by embedding a thin film of monodisperse colloidal CsPbBr3 quantum dots within a tunable optical resonator. This resonator incorporates a Gaussianshaped deformation creating a wavelength-scale potential well for polaritons. Under pulsed optical excitation, we demonstrated the emergence of polariton condensation manifested by a superlinear increase in emission intensity, a narrowing of the emission linewidth, a blueshift (Fig. 1a), and an extension of temporal coherence (Fig. 1b). Our results highlight the potential of perovskite-based colloidal quantum dots, celebrated for their remarkable optical properties and high tunability, as a cutting-edge platform for next-generation polaritonic devices.