Mn^II-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 MnII-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 MnII dopants, as well as the host-dopant energy transfer process in PNCs, we highlight that O2 can reversibly quench the MnII emission due to the temporary disturbance to the ligand field of near-surface MnII 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 MnII-doped PNCs) with phosphorescence emission.