Optical up-conversion process using tri-valent lanthanide elements hosted by lowphonon environment is helpful in wide variety of biomedical, sensing, and optical-energy harvesting applications. In up-conversion process of erbium-based nanoparticles, infra-red photons have been absorbed and converted into visible light through two-photon absorption mechanism. In this work, erbium-doped ceria and Fluoride nanoparticles, of mean diameter around 10nm, are synthesized and optically-characterized through up-conversion process. Cerium oxide (ceria) and sodium-ytterium fluoride are selected as a host due to their relativelylow- phonon medium in addition to their conductive properties. The main optical core centers, erbium atoms, are responsible for optical conversion process of the range of ~520nm emission under 780nm excitation. Then, the synthesized nanoparticles are coated on the edges of frontside of silicon solar cell in addition to the backside. The optical efficiency improvement within the up-conversion process is expected due to better spectrum utilization. The backside coating is helpful to offer a conductive medium for the generated photoelectrons to be easier moved to the electrodes. The efficiency of solar cell is found to be improved due to the coated nanoparticles to 15.20% compared to the uncoated solar cell of 15%, with a clear increase in the value of short-circuit current.