Novel erbium(III) fluorinated β-diketonate complexes with N,N-donors for optoelectronics: from synthesis to solution-processed devices

Three novel ternary Er3+ complexes emitting in the C band transmission window for fiber optic communications have been synthesised and their structures have been elucidated by single crystal X-ray diffraction. The fluorinated β-diketonate ligand, 1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedione, combines a good absorption cross-section in the ultraviolet region with reduction of non-radiative quenching of the Er3+ emission, while the rigidity and bulkiness of the three different N,N-donors (2,2′-bipyridine, bathophenanthroline and 5-nitro-1,10-phenanthroline) have a pronounced impact on the emission intensity of luminescence. Furthermore, the choice of the ancillary ligand also determines the efficiency of the antenna effect, leading to complete quenching of the ligand-associated visible emission for the optimized complex with 5-nitro-1,10-phenanthroline. Solution processed 1.54 μm organic light-emitting diodes have been manufactured and characterized for this complex, confirming the aforementioned complete resonant energy transfer from the ligands to the Er3+ ion. The features of the reported device fabrication show a simple way to obtain large area NIR-OLEDs.