High-entropy alloying in perovskite nanocrystals enables high-purity single-photon emission at room temperature

High-entropy alloying (HEA) has been shown to enhance stability and optoelectronic properties in various materials, including recent demonstrations in perovskite nanocrystals (PNCs). However, the use of HEA-PNCs outside traditional optoelectronics, specifically as single-photon sources (SPSs) for quantum information science, remains largely unexplored. Here, we demonstrate that HEA intrinsically improves the room temperature performance of PNC-based SPSs. By introducing multiple divalent cations at the Pb site, we create a high-entropy crystal lattice that facilitates exciton localization, enhancing radiative recombination while suppressing trap-assisted and phonon-mediated losses. Ab initio molecular dynamics simulations corroborate exciton localization and reveal that reduced electron-phonon coupling in HEA-PNCs diminishes exciton dephasing. Consequently, our HEA-PNCs exhibit a high single-photon emission purity of 96%, with nearly non-blinking emission at room temperature, marking the first intrinsic materials-based solution to achieve such performance. These results establish HEA as a robust design principle for next-generation room temperature PNC-based quantum emitters.