Used as a precursor in the synthesis of erbium-containing materials for optical applications, particularly in the production of upconversion phosphors and luminescent coatings. Its ability to emit in the near-infrared region makes it valuable in developing bioimaging probes and optical amplifiers for fiber-optic communications. Also employed in sol-gel processes to fabricate doped glass and thin films with enhanced photoluminescent properties. Additionally, it serves as a catalyst in certain organic transformations and is utilized in research settings for doping into host matrices to study luminescence behavior.