Highly emissive nanostructured thin films of organic host-guests for energy conversion

All-organic nanostructured host-guest systems, based on dyes inserted in the nanochannels of perhydrotriphenylene (PHTP) and deoxycholic acid (DCA), show enhanced fluorescence properties with quantum yields even higher than those of the dyes in solution, thanks to the high concentration of emissive molecules with controlled spatial and geometrical organization that prevents aggregation quenching. Both host molecules crystallize, growing with the long axis oriented along the direction of the nanochannels where the linear-chain dyes are inserted, to yield crystals emitting well-polarized light. For the DCA-based host-guests, homogeneous thin films suitable for several applications are obtained. Colour emission in such films can be tuned by co-inclusion of two or three dyes due to resonant energy-transfer processes. We show that films obtained by low-cost techniques, such as solution casting and spin-coating, convert UV light into visible light with an efficiency much higher than that of the standard polymeric blends.