Laser-assisted p-PANI/n-CdS/p-Si dual-heterojunction architecture for UV/Vis/NIR wavelength detection

In this article, a novel p-PANI/n-CdS/p-Si dual-heterostructured photodetector is constructed using combined pulsed-laser-deposited CdS and localized laser-assisted coated PANI, enabling binary independently photo-active interfaces in a single heterojunction design. The microstructural and optical examination demonstrated successful CdS and PANI formation with optical bandgaps of 2.37 eV and 1.67 eV, respectively. The intended dual-junction design revealed pronounced rectification profiles, with ratios of 9.1 and 6.7 for p-PANI/n-CdS and n-CdS/p-Si, respectively. The former exhibited an enhanced photo-detection mechanism at 460 nm with responsivity and detectivity of 45.82 mA W^-1 and 8.5 × 10¹⁰ Jones, respectively, while the latter demonstrated values of 417.75 mA W^-1 and 2.58 × 10¹¹ Jones, respectively, at 530 nm, along with remarkable performance in the NIR region (808 nm) owing to the p-Si wafer contribution. Both considered heterostructures exhibited excellent linear power dependency, with R ² ≈ 1. The dual-heterostructure demonstrated a rapid switching profile, with rise/fall times of 79/88 ms and 82/87 ms, respectively; the operational durability of the intended device revealed outstanding performance, retaining 93.7% and 87% for p-PANI/n-CdS and n-CdS/p-Si, respectively, over four weeks. The synergistic operation of the dual-heterostructure enables effective carrier separation and wavelength selection in the UV, Vis, and NIR regions, allowing an effective workflow for emerging high-performance multi-wavelength photo-detection based on hybrid organic/inorganic semiconductor design.