Pyramid-shaped quantum dot superlattice exhibiting tunable room-temperature coherent emission via oriented attachment

Coherent emission, characterized by the collective photon emission from a dense ensemble of emitters, holds great promise for quantum optics and nanophotonics applications. However, achieving robust coherent emission, particularly superfluorescence, at room temperature remains challenging due to thermal decoherence. Here, we demonstrate room-temperature tunable coherent emission from perovskite quantum dot (QD) superlattices. Our approach involves the mesocrystallization of CsPbBr₃-based QD superlattices driven by oriented attachment, which yields pyramidal-like solids with extended atomic coherency. This level of atomic-scale to nanoscale orientational structure control cannot be realized in previous QD superlattices, and it allows for quantum coherence to persist at ambient conditions. The resulting superlattices exhibit multiple narrowband emissions with exceptional spectral sharpness and tunability, reflecting the collective nature of the coherent emission. Our results establish superlattices as an emerging materials platform capable of robust quantum coherence without cryogenic constraints, opening up new possibilities for quantum optics and nanophotonics applications.