In this study, we fabricated Schottky diode devices on ZnO, Sm and Ce doped and co-doped ZnO thin films grown by the sol gel spin coating. The structural and optical properties of the sol gel films are studied, and the electrical characteristics of the Schottky diodes are investigated. The crystalline structure and surface morphology were studied using x-ray diffraction and scanning electron microscopy, respectively. Photoluminescence spectroscopy of all films measured at room temperature showed that the UV emission peak was composed of two peaks located at 388 and 405 nm and no visible light emission was detected. UV vis study revealed that the optical band gap of ZnO decreased after doping. Room temperature I-V characterization revealed a rectification behaviour of all samples. The Schottky diodes fabricated on (Sm and Ce) co-doped ZnO manifest device properties with good rectification (six orders of magnitude), low ideality factor (1.62) and barrier height of 0.82 eV.