Topological and compositional disorder induced exciton Anderson localization highly enhances luminescence quantum yields of alloyed perovskite nanocrystals

Anderson localization has inspired tremendous effort in exploring underlying physics regarding electron, atom, and photon transport in disordered lattices. However, due to the difficulty in implementing periodic trapping potential for neutral excitons, observing Anderson localization of excitons in disordered semiconductors remains challenging. We report evidence of Anderson localization of Frenkel excitons in the alloyed perovskite nanocrystals that possess high topological and compositional disorder. The broken symmetry-driven constructive interference of scattered exciton wavefunctions around the octahedrons induces strong exciton localization and, consequently, exciton–phonon coupling. This causes significant promotion of the luminescence quantum efficiency from 30% to an impressive 75% owing to enhanced radiative and suppressed nonradiative quantum transition rates. These findings clarify that both Anderson localization and exciton–lattice coupling play key roles in triggering immobility of Frenkel excitons in disordered wide-bandgap semiconductors and guide design of monocomponent warm white light emitters based on highly efficient alloyed perovskite nanocrystals.