Research Highlights

Silly defects give off white light

Biplab Das

doi:10.1038/nindia.2008.309 Published online 23 October 2008

A new nanocomposite could emit white light on being excited by near ultraviolet (UV) rays1. The nanocomposite made of zinc oxide (ZnO) and silicon dioxide (SiO2) shows intense photoluminescence. This could be useful for potential white light emitting diode (LED) applications.

The researchers produced ZnO-SiO2 nanocomposites employing sol-gel combustion synthesis using zinc nitrate, urea, tetraethoxy silane and dilute nitric acid. On being excited by near UV light, the nanocomposites gave off defect emissions. ZnO showed a strong and stable greenish-yellow defect emission. Sophisticated imaging technique showed growth of ZnO rods with highly porous structure. The rods were networked with one another over a width of 100-300 nm and connected via SiO2 amorphous structure. The high surface area of ZnO particles in SiO2 composite created defect levels supporting defect emissions.

"The nanocomposites can be considered as a potential candidate for solid state lighting device applications," said of the researchers M. S. Ramachandra Rao.

The authors of this work from: Department of Physics, Indian Institute of Technology Madras, Sardar Patel Road, Chennai, India; Materials Science Research Centre, Indian Institute of Technology Madras, Chennai, India; Department of Chemistry, Kalasalingam University, Krishnan Kovil, Sriveliputtur, Tamil Nadu, India.


  1. Thiyagarajan, P. et al. White light emitting diode synthesis using near ultraviolet light excitation on Zinc oxide–Silicon dioxide nanocomposite. Scripta Mater. 59, 722-725 (2008) | Article |