Facile fabrication of white-emitting hybrid colloids and nanocomposite films using CdSe/CdS quantum dots and zinc phthalocyanines as building blocks

Abstract

In this work, we have designed a facile protocol to prepare white emitting colloid solutions and polymer nanocomposite films via the self-assembly of zinc phthalocyanine (ZnPc) in the presence of semiconductor CdSe/CdS quantum dots (QD). Specifically, a dendritic zinc phthalocyanine showing two independent emission bands at blue (∼450nm) and red region (∼690nm) in N, N-dimethylformamide (DMF) solution was synthesized by using a biphenyl phthalonitrile based precursor. In order to fulfill the missing green emission band and overcome the strong intermolecular aggregation tendency of ZnPc that normally results to obviously quenched fluorescence in solution, an ultrasmall sized CdSe/CdS QD with green emitting capabilities, was synthesized, surface modified with a hydrophobic capping agent (oleic acid) and dispersed uniformly in nonpolar hexane. When the hexane solution of QD was introduced to the immiscible ZnPc solution in DMF, nanoconjugates exhibiting three independent emission bands can be formulated by using ZnPc and QD as building blocks via the non-covalent hydrophobic interaction established in the incompatible DMF/hexane interface. Furthermore, the white emitting ZnPc/QD colloid solutions and nanocomposite films can be readily obtained by controlling the relative concentration of ZnPc and QD.