Acta Phys. -Chim. Sin. ›› 2006, Vol. 22 ›› Issue (10): 1291-1295.doi: 10.3866/PKU.WHXB20061023

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Photoluminescent and Electroluminescent Characteristics of ZnGa2O4:Cr3+ Red Phosphor

QIAO Bin;TANG Zi-Long;ZHANG Zhong-Tai;CHEN Lei   

  1. State Key Laboratory of New Ceramics and Fine Processing, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084, P. R. China
  • Received:2006-03-31 Revised:2006-05-31 Published:2006-10-11
  • Contact: QIAO Bin

Abstract: ZnGa2O4:Cr3+ red phosphors were synthesized by citric-gel method. Typical spinel-phase ZnGa2O4 could be attained after calcined at 1000 ℃ in air ambient. According to the results of XPS and EPR, it could be deduced that Cr3+ ions were dominant in the lattice and it could not be oxidized to Cr5+ or Cr6+ after calcined in air. The emission of Cr3+ at 695 nm is originated from the transition of 2E-4A2. And due to the large overlap between absorption band of Cr3+ and emission band of the host, Cr3+ could obtain the excitation energy from the host via the effective energy transfer. The electroluminescent device was fabricated by screen printing utilizing ZnGa2O4:Cr3+ as the phosphor layer. Luminance (L) versus voltage (V) of the device match the well-known equation of L=L0exp(−bV−1/2) and the luminance increase proportionally with frequency due to the increase of excitation probability of host lattice or Cr3+ centers. The diagram of charge density (Q) versus applied voltage (V) is based on a conventional Sawyer-Tower circuit. At 280 V and 1000 Hz, the luminance and luminous efficiency of the fabricated powder EL device are about 1.0 cd•m−2 and 13 lm•W−1, respectively.

Key words: ZnGa2O4, Cr3+, Citrate-gel method, Photoluminescence, Electroluminescence