Enhanced Optical Stability of All Inorganic Perovskite Nanocrystals for Single Photon Emission

Abstract Lead halide nanocrystals are established as low cost nanostructures for realizing perovskite‐based single‐photon emitters. In 2015, Park and colleagues demonstrated the first perovskite‐based single‐photon source operating at room temperature (RT) using all‐inorganic CsPbI ₃ quantum dots (QDs). Since then, quantum light emission has been observed in various perovskite nanocrystals (PNCs) at both RT and cryogenic temperatures. Despite the remarkable features of PNCs, the use of PNCs for the incoming quantum technologies with light is restricted by their photostability and their challenging integration into photonics platforms. In this study, cryogenic µ ‐photoluminescence ( µ ‐PL) is utilized, and µ ‐Time‐Resolved Photoluminescence ( µ ‐ TRPL) spectroscopy to investigate the spectral stability of single colloidal cesium lead halide PNCs with different capping ligands. Notably, it is found that using a Zwitterionic (ZW) ligand significantly reduces the blinking effect and spectral diffusion for the cesium lead bromide PNCs, enhancing their spectral stability and reducing their µ ‐PL linewidths (≈125–140 µ eV). Additionally, a slightly longer decay time (by a factor of ≈1.35) is observed in single cesium lead bromide PNCs capped with this ZW ligand, indicating a reduction in undesirable effects such as Auger recombination. These findings can pave the way for utilizing perovskites based single photon sources as key components in quantum technology‐oriented applications.