Single-photon emitters (SPEs) in hexagonal boron nitride (hBN) are promising for quantum technologies, but their photoinstability hinders applications. This study reveals ubiquitous photobleaching in hBN vacancy emitters, characterized by two time constants: a fast, O₂-sensitive bleaching (5-10 s) and a slower process (150-220 s), potentially due to carbon-assisted defect migration. Annular dark-field scanning transmission electron microscopy (ADF-STEM) visualizes vacancy defects and carbon substitution. Thermal annealing at 850 °C eliminates both bleaching processes, achieving persistent photostability.

Sylvia Xin Li, Takeo Ichihara, Hyoju Park, Guangwei He, Daichi Kozawa, Yi Wen, Volodymyr B. Koman, Yuwen Zeng, Matthias Kuehne, Zhe Yuan, Samuel Faucher, Jamie H. Warner, Michael S. Strano