Fabrication and characterization of PANI-based sandwiched photodetector devices on n-Si and ZnO nanorods: Performance evaluation

This study focuses on the fabrication and characterization of simple sandwiched photodetector devices based on polyaniline (PANI) with various configurations: ITO/PANI/n-silicon, and ITO/PANI/ZnO nanorods (NRs)/nsilicon. The PANI polymer was synthesized from the polymerization of aniline, and the ZnO NRs were grown via hydrothermal method. The fabricated devices were analyzed via field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), and current-voltage (I-V) measurements. FESEM analysis revealed distinct PANI structures at the center and edge of the samples, with dendrites forming at the edge and mesh-like structure at the center due to solvent effect during deposition. The addition of PANI as an interlayer in the nSi/ITO junction enhanced the contact and improved carrier separation. However, the performance of the PANI-ZnO NRs devices was mixed, whereby performing better than ITO/ZnO NRs/nSi at zero bias voltage but otherwise at higher bias voltages. The thick PANI layer improved light absorption and reduced dark current but allowed increased hole-electron recombination, reducing overall performance. ITO/ PANI/nSi recorded the highest normalized photocurrent-to-dark current ratio (NPDR) at 0 V bias of 50870 W-1 under 385 nm illumination. ITO/ZnO NRs/nSi sandwiched device obtained the highest responsivity value at 0.253 A W-1 at - 8 V bias under 385 nm illumination.