Nickel Doping Unlocks Ambient-Condition Photostability in Individual Cesium Lead Bromide Perovskite Quantum Dots

Developing efficient single-photon sources is fundamental to advancing photonic quantum technologies. In particular, achieving scalable, cost-effective, stable, and high-purity single-photon emission at ambient conditions is paramount for free-space quantum communication. However, fulfilling all the requirements simultaneously under ambient conditions has remained a significant challenge. Here we present the scalable, cost-effective ambient condition synthesis of nickel-doped CsPbBr₃ perovskite quantum dots (NPQDs) using a modified ligand-assisted reprecipitation method. The resulting individual NPQDs demonstrate remarkable photostability, sustaining their performance for over 10 min under ambient conditions, and exhibit exceptional single-photon purity (>99%) with a narrow emission line width (∼70 meV). The remarkable photostability could be attributed to the spatial localization of the exciton by Ni atoms on the surface of the nanocrystal, reducing its interaction with the environment. Our results demonstrated that NPQDs with outstanding combinations of quantum emitting properties can be both synthesized and operated at ambient conditions.