An accessible approach to preparing water-soluble Mn ²⁺-doped (CdSSe)ZnS (core)shell nanocrystals for ratiometric temperature sensing

A new synthetic scheme allowing structural modifications to temperature-sensitive and water-soluble d-penicillamine-passivated Mn ²⁺-doped (CdSSe)ZnS (core)shell nanocrystals (MnQDs) was reported using air-stable chemicals. The temperature-dependent optical properties of the nanocrystals were tuned by changing their structure and composition - the ZnS shell thickness and the Mn ²⁺-dopant concentration. Thick ZnS shells significantly reduce the interference of nonradiative transitions on ratiometric emission intensities. High-dopant concentration affords consistent temperature sensitivity. In addition to the new base structure for quantum dot ratiometric temperature sensing via flexible, glovebox-free routes, the results also underscore the generalizability of the emission intensity ratio scheme for temperature sensing, originally proposed for rare-earth-doped materials.