Efficient UV photoluminescence from monodispersed secondary ZnO colloidal spheres synthesized by sol-gel method

Hsin Ming Cheng, Hsu Cheng Hsu, Shiow Lian Chen, Wen Ti Wu, Chih Chun Kao, Li Jiaun Lin, Wen Feng Hsieh

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72 Citations (Scopus)

Abstract

ZnO colloidal spheres were synthesized by sol-gel method with a narrow size distribution. We controlled the size of the spheres during the secondary reaction with various amounts of primary reaction supernatant. The optimized condition of ZnO powders with an average diameter of 185 nm was obtained for structure analysis and study of optical properties. Transmission electron microscopy and X-ray diffraction reveal that the spheres are polycrystalline in the pure wurtzite phase. Markedly enhanced near-band-edge ultraviolet photoluminescence and significantly reduced defect-related visible emission were also observed. We attribute this observation to the localized bound excitons with high density of defect states. In addition, broad yellow emission and green emission were observed when the powders were post-annealed at 500 °C in air ambience. The origins of the defect-induced visible emissions are attributed to oxygen interstitials and oxygen vacancies.

Original languageEnglish
Pages (from-to)192-199
Number of pages8
JournalJournal of Crystal Growth
Volume277
Issue number1-4
DOIs
Publication statusPublished - 2005 Apr 15

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Inorganic Chemistry
  • Materials Chemistry

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