It is expected that fluorinated organic erbium(III) complexes, of interest for optical applications at λ = 1.5 μm, have improved performance with respect to hydrogenated counterparts. However, the intrinsic radiative properties (including the absorption/emission line strengths) of organic Er 3+ complexes have not been systematically studied and compared up to date. This has precluded the observation of opto-structural correlations as well as a proper characterization of the infrared f-f transitions and thus a lack of meaningful figures for the optical efficiency of these materials at the 1.5 μm emission. We have performed a complete opto-structural correlation study of the oscillator strengths of the f-f transitions of hydrogenated and fluorinated organic erbium(III) complexes, including a Judd-Ofelt analysis. The Judd-Ofelt analysis on the crystals has allowed the study of the interdependence of the chemical nature, structure, and spectroscopic behavior. We observe clear trends that can help the design and understanding of these important infrared emitters for phosphor and opto-electronic applications.