Significant improvement in dopant emission and lifetime in water soluble Cu:ZnSe/ZnS nanocrystals

We report here the enhanced dopant emission in Cu:ZnSe/ZnS core-shell nanocrystals (NCs) through an aqueous route in ambient conditions. A three-fold quantum enhancement in luminescence has been achieved by developing a ZnS inert shell as compared to the pristine doped NCs. The internal doping of Cu after shell growth, signifying localization of Cu2+ t(2) energy states in the deep band gap, has shown a significant improvement in dopant excited state lifetime. The long lifetime related to Cu dopant emission is the longest lifetime ever reported for copper doped zinc based NCs developed through an aqueous route. The good colloidal as well as the luminescence stability of these highly efficient doped NCs mean they have great potential for use in biomedical imaging applications.