More than 40% of the world’s energy consumption occurs within buildings and a significant fraction of these costs are associated with the lighting of interiors. The replacement of fluorescent compacts with solid-state light-emitting diodes (LEDs) is expected to bring about an almost five-fold reduction of energy consumption. However, there is a strong need to develop red, green, and blue phosphors that can be coupled with blue LEDs to generate white light. Rare-earth oxychlorides (REOCl) show great promise as color tunable phosphors given their ability to readily accommodate multiple luminescent centers. These compounds crystallize in a structural motif that alternates cationic (REO)nn+ and anionic (Cl-) layers and allows for efficacious energy transfer to luminescent rare-earth dopant atoms. These compounds are further characterized by a low maximum phonon cutoff energy and exhibit high chemical stability. An ongoing challenge is the development of synthetic methods for the controllable incorporation of multiple luminescent centers within the oxychloride lattice. The synthesis of solid-solution REOCl nanocrystals has been performed using the non-hydrolytic sol—gel condensation of trivalent rare-earth alkoxides and rare-earth chlorides. Luminescent centers have been incorporated by substituting a desired molar equivalent of the dopant rare-earth chloride (Eu3+, Eu2+, and Tb3+) with the rare-earth chloride (Gd3+ or La3+) precursor. The prepared nanocrystals have been characterized via X-ray diffraction, transmission electron microscopy, spectrofluorescence, inductively coupled plasma-mass spectrometry, and X-ray excited optical luminescence. The judicious incorporation of dopants allows for precise control over the emission wavelength, lifetime, and photoluminescence intensity of the obtained materials. The luminescence behavior observed upon optical activation and X-ray excitation are starkly different with the latter being characterized by a pronounced modulation in proximity of the giant resonance.

Red, white, and blue: Controlling the luminescence of doped rare-earth oxychloride nanocrystals by ligand selection and compositional modulation

253rd National Meeting (2017)

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