Room temperature collective blinking and photon bunching from CsPbBr3 quantum dot superlattice.

Development of quantum systems supporting collective many-body states is crucial for advancement of quantum technologies, and perovskite quantum dots (QDs) have emerged as promising quantum light sources. However, photon bunching, a key signature of collective states, has been observed in perovskites only at cryogenic temperatures. Here, we report collective blinking and photon bunching in perovskite QD superlattices at room temperature. Sub-wavelength-sized CsPbBr3 superlattices exhibit distinct two-level blinking, and demonstrate photon bunching with a degree of up to 3.9. Time-resolved photoluminescence and super-resolution imaging reveal long lifetime components, and emission spatially confined to regions tens of nanometers in size, observations consistent with long-range exciton migration to a localized energy trap within the superlattice. Power-dependent degree of bunching and analysis of the bunching dynamics point to biexciton-exciton cascade emission as the origin of photon bunching. These findings establish perovskite QD superlattices as a promising platform for room-temperature collective optical phenomena.