Near UV excitable yellow light emitting Zn doped MgO for WLED application

摘要

Nanoparticles of Mg_(1-x)Zn_x)O(x = 0, 0.05, 0.1, 0.15) were synthesized by sol-gel assisted combustion method and their optical properties has been investigated. Crystal structure, phase purity and doping of Zn~(2+) ions in MgO are confirmed from Powder X-ray diffraction method. Spherical shape porous particles are found with increasing particle density as a function of doping concentration. Doping of Zn ions in MgO has altered the optical band gap of MgO and reduced the band gap from 4.6 eV to 3.9 eV as the concentration of Zn increases. The optical absorption bands are observed in the visible region exhibited the presence of various defects such as F, F~+, F~(2+) in MgO and these defects concentration increases with Zn doping. The photoluminescence emission spectra of Zn doped MgO shows a bright bluish green emission which starts from 450 nm to 570 nm and this light can be obtained at the excitation of near UV light from 330 to 380 nm. However, the same defective structure has led to a highly intense broad band emission which starts from 450 nm to 750 nm at the excitation of near UV LED (at 375 nm). This material can be used as a yellow emitting phosphor for phosphor converted white LEDs (PCWLEDs) at the excitation of near UV LEDs.