PbI 2 for Broadband Detection: A Review of Photodetectors, Xray Imagers, and γ-ray Sensors

Lead iodide (PbI2) is a versatile semiconducting material for wide spectrum detection applications, including photodetectors, X-ray imaging devices and γ-ray sensors. It has a crystalline structure, large bandgap and high atomic number, which make it efficient at absorbing photons, tunable in its electrical properties and flexible. Recent developments in synthesis strategies such as Pulsed Laser Ablation, Pulsed Laser Deposition, Spray Pyrolysis, Chemical bath deposition and Physical vapour deposition have resulted in nanostructures and thin films with improved responsivity, detectivity and spatial resolution. Targeted doping (Ag, Zn, Sn, graphene oxide) and heterojunction engineering (PbS/PbI 2 , PbI 2 /CdSe, Au@PbI 2 ) enhance spectrum sensitivity and optimize charge transport. Photodetectors based on PbI 2 now have responsivities over 300 A/W and detectivities of 10 15 Jones, and flexible thin films reliably detect X-rays when mechanically flexed. In γ-ray spectroscopy, crystals grown by zone melting and by the vertical gradient freeze method have higher energy resolution and carrier mobility, illustrating the importance of defect engineering. While HgI 2 and CdTe are the gold standard in sensitivity, PbI 2 offers unique advantages in scalability, mechanical flexibility and new defect passivation methods. Continuous improvements in large-area deposition, dark-current suppression and hybrid integration make PbI 2 an attractive candidate for next-generation medical diagnostics, environmental monitoring, wearable electronics and nuclear safety applications.