Rapid microwave synthesis of white light emitting magic sized nano clusters of CdSe: role of oleic acid

Abstract

A rapid, green and one-pot microwave synthesis of magic sized nano clusters (MSNCs) of CdSe is presented by use of various cycloalkeno-1,2,3-selenadiazoles as a selenium source. The effect of different parameters i.e. time, surfactant and solvent on the morphology and the cluster size have been investigated. Oleic acid (OLA) is preferred as the capping agent which promotes the growth of MSNCs due to a long carbon chain structure and also due to its non-interaction with the CdSe surface, chemically. The optical spectroscopy studies (UV-visible and PL) revealed the formation of various clusters of CdSe MSNCs families having band gap absorptions at 390 and 450 nm (CdSe₁₃ to CdSe₃₄). The combination of various clusters in the sample leads to white light emission when illuminated under a 365 nm UV light source. It is believed that, in the present studies the white light is generated by well known surface related defects due to large non-coordinating Se or Cd atoms on the surfaces. The samples were thoroughly characterized and stable white light emission was observed for more than 2 months.