Excitation-dependent negative photoconductive transport and multistate electrical recognition in a CdO/SnO₂ heterogeneous network

Excitation-dependent negative photoconductive transport is demonstrated in a heterogeneous CdO/SnO₂ particulate network, revealing the interplay between optical excitation and electric-field-driven charge transport. Structural and optical analyses identify a biphasic architecture with diverse emissive states. Under 266, 447, and 532 nm illumination, the device exhibits reproducible negative current modulation, with the suppression magnitude governed by photon flux and bias conditions. Dual-wavelength excitation further enables four distinguishable electrical states, achieving a mean per-state recall of 94.5% in repeated measurements from a single device. The excitation-dependent NPC behavior is consistent with photoinduced transport modulation involving carrier trapping, mobility variation, and interfacial or transport-barrier effects, although the microscopic origin remains unresolved.