Article pubs.acs.org/IC
A Garnet-Based Ca2YZr2Al3O12:Eu3+ Red-Emitting Phosphor for n‑UV Light Emitting Diodes and Field Emission Displays: Electronic Structure and Luminescence Properties Xicheng Wang,†,‡ Zhengyan Zhao,†,‡ Quansheng Wu,†,‡ Yanyan Li,†,‡ and Yuhua Wang*,†,‡ †
Key Laboratory for Special Function Materials and Structural Design of the Ministry of the Education, and ‡Department of Material Science, School of Physical Science and Technology, Lanzhou University, Lanzhou, 730000, China S Supporting Information *
ABSTRACT: A series of Ca2YZr2Al3O12:Eu3+ (CYZA) phosphors were successfully synthesized through conventional solid-state method. The electronic structure and their photoluminescence or cathodoluminescence properties were investigated in detail. Under n-UV excitation, the CYZA:Eu3+ exhibits more intense red emission than the commercial Y2O3:Eu3+ phosphor. A WLED lamp with good color render index was obtained by fabricating the phosphor with BAM:Eu2+ and LuAG:Ce3+ phosphors. The phosphor also exhibits red emission with high current saturation and high resistance under low voltage electron bombardment. The degradation resistance can be compared to the commercial Y2O3:Eu3+ phosphor. All the results indicate that the CYZA:Eu3+ has potential applications in both white LEDs and FEDs. Moreover, when it comes to display issues, field emission displays (FEDs) have been considered as the new-generation flat panel display technique and attracted great attention. FEDs have many advantages including self-emission, thin panel, wide viewing angle, short response time, high brightness, high contrast radio, and low energy consumption.5,6 The FED devices are basically composed of field emitter cathodes arrays and phosphor anodes.7 The luminescence properties of phosphors determine the display performance such as energy efficiency and images quality.8 In the practical application of FEDs, operating conditions with low excitation voltage (≤5 kV) and high current have become the mainstream.9 Thus, phosphors for FEDs should possess high luminescence efficiency and good stability under such excitation conditions. The sulfide-based red-emitting phosphor exhibits high efficiency and has been used as a commercial red phosphor. However, under electron-beam bombardment, sulfide compounds can easily resolve and release sulfide gases, which may lower the luminescence efficiency of phosphors and the performance of the FED devices.8 Therefore, it is still urgent to find red phosphors with good chemical durability.
1. INTRODUCTION As the increasing worldwide awareness of environmental protection, energy conservation, and sustainable development, people are searching for novel technology fulfilling these demands in the fields of illumination and display.1,2 In the past decades, white light-emitting diodes (WLEDs) have been considered as the promising solid-state light source to replace traditional incandescent and fluorescent lamps due to their advantages such as energy-saving, environmental friendliness, and long lifetime.3 The most commercially used method to generate white light is combining the blue chip with yellow phosphors. Although this method shows high photoluminescence efficiency under blue light excitation, the color rendering index (CRI) is poor (
