Luminescent erbium-based inorganic-organic hybrid materials play an important role in many frontier nano-sized applications, such as amplifiers, detectors and OLEDs. Here, we demonstrate the possibility to fabricate high-quality thin films comprising both erbium and an appropriate organic molecule as a luminescence sensitizer utilizing the combined atomic layer deposition and molecular layer deposition (ALD/MLD) technique. We employ tris(N,N'diisopropyl-2-dimethylamido guanidinato)erbium(III) [Er(DPDMG)3] together with 3,5pyridine dicarboxylic acid (3,5-PDA) as precursors. With the appreciably high film deposition rate achieved (6.4 Å/cycle), the guanidinate precursor indeed appears as an interesting new addition to the ALD/MLD precursor variety towards novel materials. Our erbium-organic thin films showed highly promising UV absorption properties and a photoluminescence at 1535 nm for a 325 nm excitation, relevant to possible future luminescence applications.