<p>A novel dual-doping incorporating Ce₇O₁₂@La (2, 4, and 6 wt%) into ε-Pr₅O₉ thin films is systematically investigated to realize high-performance photodetector devices. The films were successfully fabricated using a cost-effective Jet Nebulizer Spray Pyrolysis (JNSP) technique, ensuring excellent thickness uniformity and reproducibility over large areas. X-ray diffraction analysis reveals a distinct doping-induced crystal phase transition from monoclinic to rhombohedral ε-Pr₅O₉, indicating effective lattice modification and improved structural stability. Field-emission scanning electron microscopy confirms nanoporous morphology, for enhanced light absorption and carrier transport. The successful incorporation of Pr, Ce, and La elements is verified through energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy, confirming the formation of a chemically stable dual-doped. Optical investigations using UV–Vis spectroscopy demonstrate a gradual reduction in optical bandgap from 3.62 to 3.37&#xa0;eV with increasing dopant concentration, enhanced optical absorption in the UV–visible region. Electrical characterization of the Cu/ε-Pr₅O₉:(Ce₇O₁₂@La)/n–Si MIS diode under dark and illuminated conditions reveals improved charge transport behavior with suppressed leakage current, highlighting superior interfacial quality. Notably, the optimized device exhibits a high quantum efficiency of 279.2477 × 10⁻⁴% and a detectivity of 6.7434 × 10⁷ Jones, demonstrating its strong photodetection capability. The synergistic interaction between Ce₇O₁₂ and La dual dopants effectively modulates the structural, optical, and electrical properties of ε-Pr₅O₉, positioning this rare-earth-oxide-based MIS structure as a promising platform for next-generation optoelectronic and photodetector applications.</p> Graphical Abstract <p></p>