Effect of External Stimuli on the Semiconducting Behavior of Silk Fibers

ABSTRACT Natural semiconducting fibers have recently attracted significant attention due to their potential applications in flexible electronics, optoelectronic devices, and environmentally sustainable technologies. In this work, the electrophysical and photoelectrical properties of AGU‐112 silk fibers were systematically investigated with special emphasis on the influence of chemical doping and external physical factors. Undoped and chemically modified samples were prepared by incorporating Al 2 (SO 4 ) 3 and CuSO 4 dopants, followed by controlled thermal treatment. The temperature‐dependent electrical conductivity of the silk fibers was measured over a wide temperature range, revealing a pronounced exponential increase in conductivity with temperature, which confirms the semiconducting nature of the material. Activation energies were determined from Arrhenius analysis, yielding E ₜ₁ = 1.20 eV, E ₜ₂ = 0.49 eV for Al 2 (SO 4 ) 3 ‐doped fibers, and E ₜ = 1.85 eV for CuSO 4 ‐doped fibers. Photoconductivity kinetics were examined under ultraviolet illumination (hν = 5.0 eV). The doped silk fibers exhibited a significant increase in photocurrent during UV exposure and a distinct relaxation behavior after the light source was switched off, demonstrating the presence of an internal photoelectric effect. The linear current–voltage characteristics observed in all samples indicate stable ohmic conduction. The obtained results demonstrate that AGU‐112 silk fibers, when appropriately modified, behave as functional semiconducting materials and exhibit strong photoresponsive properties, making them promising candidates for application in bioelectronic and optoelectronic devices.