Colloidally synthesized and bandgap-engineered luminescent titanium nitride quantum dots

Semiconductor nanomaterials, such as cadmium, lead, and mercury chalcogenides, as well as lead halide perovskites, exhibit excellent optical, electronic, photonic, and photovoltaic properties, making them promising for applications in solar cells, LEDs, and X-ray photodetectors. However, heavy metals in these nanomaterials raise concerns about their use in devices and the recycling and disposal of such devices. Therefore, developing greener luminescent materials is crucial for sustainable optoelectronic and photovoltaic technologies. We report a colloidal chemical method for engineering brilliantly luminescent titanium nitride (TiN) quantum dots showing tunable optical bandgap (1.8-2.2 eV) and multicolor photoluminescence. We demonstrate the TiN quantum dot structure and properties using HRTEM, SEM-EDX, XRD, XPS, Raman spectroscopy, and steady-state and time-resolved fluorescence spectroscopy, confirming their size, morphology, chemical composition, crystalline structure, bandgap, and luminescence properties. This research presents luminescent TiN quantum dots as promising substitutes for metal chalcogenides and lead halide perovskites in sustainable electrooptical and photovoltaic technologies.