Ruthenium-Doped InP Quantum Dots for Efficient Red Emission

The synthesis of various transition-metal-doped InP quantum dots (QDs), such as copper, manganese, and silver, for enhanced optoelectronic properties has been reported to date. Herein, we introduce ruthenium (Ru) doping into InP QDs. After Ru doping, InP QDs showed a significant red shift up to 325 meV due to the introduction of mid-gap states. The optimization studies of the ZnS shell formation on Ru-doped InP core QDs led to a high photoluminescence quantum yield (PLQY) of 77.6% in the red spectral region, while without ruthenium doping the PLQY reached a maximum level around 60% via the same synthetic approach. Elemental mapping, mass spectrometry, and lattice change confirmed the incorporation of Ru inside the InP QDs. Moreover, the integration of Ru-doped QDs into LEDs in a liquid matrix led to an external quantum efficiency of 7.9%. This study demonstrates that Ru doping can be an alternative strategy for efficient red emitters.