Search

Highlyfluorescent, discotic trioxatriangulenium dyes were alignedby simple spin-casting on substrates with friction transferred PTFElayers. The fluorescent crystalline thin films show near perfect macroscopicalignment on centimeter large areas directly from spin-casting. GracingIncidence X-ray Diffraction (GIXD) unambiguously allowed the determinationof a long-range order unit cell as well as its orientation with respectto the PTFE fibers. Further analysis of the X-ray data, in conjunctionwith polarized absorption spectroscopy, suggest a lamellar packingmodel with alternating layers of alkyl chains and ionic dyes orientedparallel to the substrate. This structure results in a highly anisotropicelectrostatic potential around the cationic chromophore, causing significantshifts in energy and orientation of the optical transitions. Thus,the optical properties of the material are, to a large extent, controlledby the position of the otherwise inert PF6–counterions. The bright fluorescence from the films is also polarizedparallel to the PTFE alignment layer. Doping of the thin films withfluorescent energy acceptor traps shows that efficient exciton migrationtakes place in the thin films. The excellent exciton transfer capabilities,in conjunction with the perfect alignment, might be of interest infuture applications in solar energy harvesting or as thin film sensors. [ABSTRACT FROM AUTHOR]