Optical and electrical properties of ZnGa2O4/Mn2+ powder electroluminescent device

We developed a powder electroluminescent device using ZnGa2O4/Mn2+ phosphor with particle size of 2 mum. Optical and electrical properties of powder electroluminescent device were investigated. This device emits green color of 505 nm with a half width of 25 nm. The green emission occurs at the falling edge of applied voltage. The origin of green color is explained in terms of the energy transfer from hot carriers to Mn2+ centers via self-activated Ga-O centers. The relationship between luminance (L)-applied voltages (V) matches well-known equation of L = L(o)exp(-bV(-1/2)). Luminance is linearly dependent on frequency due to the increase of excitation chances of host lattice or Mn2+ ions with increasing frequency. The emission color of ZnGa2O4/Mn2+-based EL device is not influenced by both frequency and applied voltage. The luminance and luminous efficiency at sinusoidal voltage of 180 V and frequency of 400 Hz are about 1.0 cd/m(2) and 15 lm/W, respectively. Thus, our fabricated powder electroluminescent device with ZnGa2O4/Mn2+ phosphor shows chemical stability along longer lifetime in comparison with the existing ZnS powder electroluminescent device. (C) 2003 Elsevier B.V. All rights reserved.