Molecular Water Lilies: Orienting Single Molecules in a Polymer Film by Solvent Vapor Annealing

摘要

The microscopic orientation and position of photoactive molecules is crucialto the operation of optoelectronic devices such as OLEDs and solar cells. Here,we introduce a shape-persistent macrocyclic molecule as an excellentfluorescent probe to simply measure (i) its orientation by rotating theexcitation polarization and recording the strength of modulation inphotoluminescence (PL), and (ii) its position in a film by analyzing theoverall PL brightness at the molecular level. The unique shape, the absorptionand the fluorescence properties of this probe yields information on molecularorientation and position. We control orientation and positioning of the probein a polymer film by solvent vapor annealing (SVA). During the SVA process themolecules accumulate at the polymer/air interface, where they adopt a flatconformation, much like water lilies on the surface of a pond. The results aresignificant for OLED fabrication and single-molecule spectroscopy (SMS) ingeneral.