Fluorescence intermittency and spatial localization of core-shell quantum rod clusters in an inverse nematic gel

Abstract

Formation of stable dispersions of CdSe/CdS core-shell quantum rods (CSQRs) in an inverse nematic gel (N-gel) is reported. The CSQRs distribute uniformly in the N-gel matrix and spontaneously form an ordered arrangement of bright clusters. Estimates show that \ensuremath{\sim}90% of CSQRs are homogeneously dispersed and \ensuremath{\sim}10% form clusters in the N-gel phase. Optical properties exhibited by individual CdSe/CdS CSQRs are retained in the dispersions, including a moderate polarization dependence. Extensive fluorescence confocal microscopy studies show evidence for suppressed fluorescence blinking of the clusters in the N-gel phase. The spatial constancy of such clusters is another attractive feature which makes them suitable as stable nanoemitters. The results are interpreted in terms of the unusual type of distribution of the helical gelator fibers in the N-gel phase which promotes self-assembly of the CSQRs and interactions within the clusters.