Tunable-color luminescence via energy-transfer in composite YAG:Ce/TTA for white light application

Herein, we report the detailed structural and spectroscopic analysis of novel composite material synthesized by attaching an organic ligand, 2-Thenoyltrifluoroacetone (TTA), on the surface of Cerium doped Yttrium Aluminum Garnet (YAG:Ce) nanophosphor. The synthesized nanophosphors are characterized by experimental techniques related to material characterization and spectroscopy viz. XRD, SEM, FTIR, DLS, Zeta potential, PL and decay curve analysis, etc. A detailed comparative study was made based on different analysis techniques. We have monitored the emission spectra at various excitations (350 nm, 405 nm, 450 nm, and 465 nm) and observed that the emission intensity of YAG:Ce/TTA enhanced significantly by factor of ~ 35%. We established the energy transfer from TTA molecules to YAG:Ce on the basis of the extension of emission profile of composite nanophosphor on excitation of TTA molecules. To estimate the radiative lifetime, decay curves of the synthesized samples were monitored on excitation with 360 nm wavelength. For 360 nm excitation, lifetimes of the TTA molecules was found to be slower by ~ 02 ns in the case of composite nanophosphor indicating the energy transfer from TTA molecules to Ce³⁺ ions. The TTA sensitized composite nanophosphor manifest the significantly modified CIE coordinates as compared to the YAG:Ce nanophosphor was observed to be (0.37, 0.60). Also, the CIE coordinates and color correlation temperature (CCT) of composite nanophosphor is studied as a function of laser power. The detail photo-physics of the observed modification is well explained.