Insight into the spectroscopic behavior of Dy <sup>3+</sup> ‐substituted and Li <sup>+</sup> charge–compensated molybdate phosphors
Priyanka Nayak, Sushri Sangita Nanda, Santosh K. Gupta, K. Sudarshan, S. Dash
Abstract
Abstract Efficient utilization of phosphors in solid‐state lighting and phosphor‐converted light‐emitting diodes demands high emission intensity, narrow size distribution, and tunable luminescence. Here in this work, un‐doped and Li + co‐doped CaMoO 4 :Dy 3+ nanoparticles are synthesized via modified reflux method in ethylene glycol medium at 130°C. The host shows broad dual band emission centered in blue and green regions endowed by charge transfer and defects. Upon Dy 3+ doping, the host‐to‐dopant energy transfer causes the CaMoO 4 :Dy 3+ nanoparticles to exhibit characteristic emission lines from Dy 3+ . The Commission Internationale de L'Eclairage (CIE 1931) chromaticity coordinates for the prepared phosphors are estimated and found to lie in the nearly white region of color space. The light output as well as excited state lifetimes are successfully improved by lithium co‐doping by virtue of reduced charge compensating defects and sensitization via oxygen‐related defects. The positron annihilation studies show that all the lithium concentration co‐doped for charge compensation is merely helping in the removal of cations. This work shows the role of lithium co‐doping and its optimum concentration in improving the optical properties of phosphors.