Abstract This work presents an extensive investigation on the synthesis, structural characterization, optical evaluation, and device applications of Er-doped and Er-Yb co-doped ZnO thin films prepared via a citric acid-assisted sol-gel process combined with spin coating. Pd/ZnO:Er and (Er/Yb)/n-Si/Au-Sb Schottky barrier diodes were fabricated using resistive evaporation technique for precise contact deposition. The impact of Er and Er-Yb codoping on structural, optical, and electrical properties, as well as device performance was compared in detail, providing insights into rare-earth codoping strategies for high-performance optoelectronic devices. X-ray diffraction (XRD) analysis confirmed the retention of the hexagonal wurtzite structure in all films, with minor shifts in peak positions indicating successful doping. Optical characterization revealed a slight widening of the bandgap in co-doped films, attributed to the dopant effect. Electrical measurements of SBDs demonstrated improved rectification ratios, lower ideality factors, and higher barrier heights in co-doped films compared to undoped Er doped counterparts. These findings underscore the efficacy of Er/Yb co-doping in modulating the properties of ZnO thin films for advanced optoelectronic applications.