Eu3+ as a spectroscopic probe to understand local site-luminescence correlation in novel Y2TiO5:Eu3+ phosphor

Abstract

Red emitting phosphor materials play a very important role in improving the color rendering index and lighting efficiency of phosphor-converted white light-emitting diodes (pc-WLEDs). However, the research pertaining to design and development of the same has somehow saturated with real lack of novel compositions and functionalities. In this work, a sincere effort has been vested in designing relatively new compositions Y2TiO5:x%Eu3+(x = 1–10) using simple solid-state reactions for efficient, narrow and pure red emission. Europium is distributed at both Y(1) and Y(2) site with higher excited state lifetime. Under the optimal mid and near ultraviolet light excitation, Y2TiO5:5%Eu3+shows a strong red emission at 608 nm with a high color purity of 99.96% and a moderate internal quantum efficiency of 13%. Impressively, this red-emitting phosphor exhibits a concentration quenching at 5.0 mol%, internal QY of ∼34%, lower non-radiative channels and higher branching ratio. Trend in Judd-Ofelt parameter suggested that there is monotonic increase in degree of distortion and as the concentration increases Eu-O bond becomes highly polarizable. This work and the obtained results suggested that Y2TiO5:Eu3+ phosphor has great potential to serve as red emitting phosphor for pc-WLEDs, opening a new perspective for developing new titanate-based luminescent materials.