Purpose <p>Double-heterojunction photodetectors have attracted significant attention because they enable high-performance broadband photodetection through enhanced interfacial charge transfer and optimized energy band alignment. This study aims to fabricate and characterize a ZnO/PbI₂/p-Si bilayer heterojunction photodetector prepared by pulsed laser deposition (PLD).</p> Methods <p>Lead iodide (PbI₂) and zinc oxide (ZnO) thin films were sequentially deposited onto a p-type silicon substrate using the PLD technique. The structural, optical, and morphological properties of the deposited films were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The electrical and photoresponse characteristics of the PbI₂/Si and ZnO/PbI₂/Si photodetectors were investigated under dark and illuminated conditions through current–voltage (I–V) measurements.</p> Results <p>XRD analysis confirmed that both ZnO and PbI₂ thin films were crystalline with hexagonal wurtzite structures and exhibited a preferred orientation along the (002) plane. SEM observations revealed spherical PbI₂ and ZnO nanoparticles with average particle sizes of 31 nm and 29 nm, respectively. The PbI₂/Si photodetector exhibited a maximum responsivity of 1.1 A/W at 550 nm, whereas the ZnO/PbI₂/Si photodetector achieved an enhanced responsivity of 1.92 A/W at 500 nm. The corresponding external quantum efficiencies were 176.4% for the PbI₂/Si photodetector and 549.7% for the ZnO/PbI₂/Si photodetector. In addition, the equilibrium energy band alignment of the ZnO/PbI₂/Si heterojunction was established.</p> Conclusion <p>Deposition of the ZnO layer on PbI2 film significantly enhances the photoresponse of the PbI₂/Si heterojunction, demonstrating that the ZnO/PbI₂/p-Si bilayer heterojunction is a promising architecture for high-performance broadband photodetectors.</p>