Bright white light emitting Eu and Tb co-doped monodisperse In ₂O₃ nanocrystals

Bright light emitting monodisperse In_2-(x+y)Eu _xTb_yO₃ (x = 0.05, 0.1, 0.15, 0.2 and y = 0.05, 0.1, 0.15) nanocrystals were successfully synthesized by a versatile hot-injection colloidal route. The X-ray diffraction and X-ray photoelectron spectroscopy studies clearly showed that Eu and Tb were incorporated into the In₂O₃ lattice. Surface adsorbed NO₃^- and Cl^- anions of Eu³⁺ and Tb³⁺ precursors assist the formation of flower like morphology through the oriented attachment process. Optical absorption spectra have been interpreted in terms of 4f → 5d (Eu, Tb) and 2p(O) → 5d (Eu, Tb) interband transitions. The observation of characteristic emission peaks related to Eu³⁺ and Tb³⁺ by indirect excitation suggests that In₂O₃ is an efficient sensitizer. Proper tuning of the compositions, 15% of Eu and 10% of Tb, gives the most intense white light and excellent chromaticity co-ordinates (0.35, 0.35). The shortening of lifetime with Eu and Tb doping improves the energy transfer from the host In₂O₃ to dopant Eu³⁺ and Tb³⁺ ions.