Tunable white light emission from a single-host phosphor Gd 2 MoO 6 :Eu 3+ ,Dy 3+ for near ultraviolet light-emitting di
- PDF / 499,476 Bytes
- 8 Pages / 584.957 x 782.986 pts Page_size
- 103 Downloads / 163 Views
A series of Eu31 and Dy31 singly and doubly doped Gd2MoO6 phosphors were synthesized with solid state reactions. The X-ray powder diffraction analysis of phosphors shows that substitution of Eu31 and Dy31 does not change the host structure of phosphors. The absorption spectra measurements show that un-doped Gd2MoO6 can absorb near ultraviolet light without any visible light emission. However, energy absorbed by Gd2MoO6 can be effectively transferred to doped Eu31 and Dy31 and makes them emit blue, yellow, and red light, respectively. White light can be obtained by combining blue, yellow, and red emission. The doping of Dy31 plays a major role for the formation of white light. The introduction of Eu31 can remarkably decrease the color temperature of the white light emission. The measurement of the temperature-dependent luminescent properties indicates that the phosphors present a good thermal stability. Our investigation indicates that Gd2MoO6:Eu31,Dy31 is a potential candidate for white light emitting diodes applications. It also provides a new sight for the achievement of white light emission.
I. INTRODUCTION
Nowadays, white light-emitting diodes (LEDs) have attracted much attention due to their advantages over existing incandescent and fluorescent lamps, such as high efficiency, compactness, long operational lifetime, and environmental friendliness. Therefore, researchers have developed several technologies combining blue and near ultraviolet (NUV) LED chips to generate white light.1,2 The first method uses blue LED chips and yellow YAG: Ce31 phosphors, exhibiting both high luminescence efficiency and high color temperature.3,4 The second method uses the combination of NUV LED chips and the red, green, blue light emitted from several phosphors, exhibiting a low color temperature and a low luminous efficiency due to the light re-absorption among different phosphors.5,6 Thus, developing single-host full-color phosphors has been a popular technique for white LEDs.7–13 There are many approaches for the generation of white light from single-host phosphors. Several color lights which consist of white light can be obtained from either one activator [such as Dy31 (Ref. 14–16)], two activators (such as Eu21 and Mn21,17–23 Ce31, Tb31, and Mn21,24–26 and so on), or one activator and the host.27,28 In the present paper, we developed a new approach for the generation of white light. Eu31 and Dy31 co-doped Gd2MoO6 phosphors were prepared with solid state reactions. White light can be obtained from the combination of blue, yellow light from Contributing Editor: Winston V. Schoenfeld a) Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2016.465
Dy31 and red light from Eu31. This phosphor can be excited with NUV LEDs efficiently. With this approach, reduction is unnecessary and the color temperature can be tuned conveniently. II. EXPERIMENTAL
All the investigated phosphors were synthesized with traditional solid state reactions. Firstly, raw materials Gd2O3 (99.99%), MoO3 (99.0%), Eu2O3 (99.99%),
Data Loading...
