PMMA or PVDF films blended with β-diketonate tetrakis EuIII or TbIII complexes used as downshifting coatings of near-UV LEDs

Abstract

Luminescent Ln^III complexes incorporated in polymeric films exhibit narrow emission bands and absorption within the near-UV/blue spectral range, and enhanced phostability, which qualify them to be explored for solid-state lighting. Herein, (C₂₆H₅₆N)[Eu(dbm)₄] and Na[Tb(acac)₄], (C₂₆H₅₆N⁺ = didodecyldimethylammonium, dbm⁻ =1,3-diphenyl-1,3-propanedionate, acac⁻ = acetylacetonate), were dispersed in PMMA or PVDF films to protect them from degradation, and the obtained blends were applied as downshifting coatings on near-UV emitter LEDs. Upon such excitation, both Eu^III and Tb^III complexes emit red or green light with absolute emission quantum yields of 6.4 and 99%, respectively. The complex amount within films influences the photophysical parameters due to multiphotonic deactivation, and formation of agglomerates. For the PMMA-based LED prototypes, the Ln^III emission is well-observed while for the PVDF ones, only a poor Ln^III emission is detected due to their opacity. Therefore, the PMMA-based systems are better candidates to be used as luminescent coatings of near-UV LEDs for solid-state lighting.