Selective luminescence enhancement of lanthanide complexes using diffraction gratings

Linear and superimposed diffraction gratings have been designed to selectively enhance light emission at specific wavelengths from thin films of lanthanide complexes at multiple luminescent transitions. Optimal grating pitches were determined through numerical modeling and the gratings were fabricated on photoactive azobenzene films, then transferred through nano-imprint lithography, to a bilayer of a europium dye-doped polymethyl methacrylate thin film mounted on an epoxy layer. The optimized gratings were found to increase emission intensity by up to ninefold at the emission wavelengths through angle-dependent out-coupling of waveguiding modes. This strategy was extended to simultaneously increase the emission intensity of multiple bands of the europium dye at the emission wavelengths by using a triple parallel-superimposed grating. This work demonstrates how diffraction gratings on thin films can be readily designed and manufactured for tunable angular control and wavelength-specific enhancement of emission bands from thin films doped with dyes.