MnII-Doped Cesium Lead Chloride Perovskite Nanocrystals: Demonstration of Oxygen Sensing Capability Based on Luminescent Dopants and Host-Dopant Energy Transfer

The design of photoluminescence-quenching probes for molecular oxygen (O₂) is always a large space to explore. Luminescent semiconductor nanocrystals (NCs) have been proposed as emerging oxygen-responsive probes, but the inherent O₂ sensing of phosphorescent semiconductor NCs has not been reported so far. Here, we demonstrate the O₂ sensing capability of Mn^II-doped CsPbCl₃ nanocrystals (Mn:CsPbCl₃ NCs) and reveal the role of O₂ on the optical de-excitation process of such perovskite nanocrystals (PNCs). By adjusting the amount and distribution of Mn^II dopants, as well as the host-dopant energy transfer process in PNCs, we highlight that O₂ can reversibly quench the Mn^II emission due to the temporary disturbance to the ligand field of near-surface Mn^II dopants in PNCs. In phosphorescence mode, the photoluminescence intensity of the Mn:CsPbCl₃ NCs is quenched by 53% on increasing O₂ concentration from 0 to 100%. The Stern-Volmer plot shows a good linear in the 0-12% O₂ concentration range. High sensing reversibility and rapid signal response are also achieved. In our perception, the mechanism study makes our PNCs candidates for the optical probes of O₂, and it is enlightening to explore more possibilities of the inherent O₂ sensing based on the semiconductor-doped NCs (not restricted to Mn^II-doped PNCs) with phosphorescence emission.