pani/htmt microstructured composites for low-temperature optical sensing

Abstract This work reports the synthesis and characterization of a PANI/HTMT microstructured composite engineered for low-temperature optoelectronic sensing. The material was prepared by in situ chemical oxidative polymerization of aniline in the presence of hydrogen titanate microtubes (HTMTs). Structural and spectroscopic analyses reveal strong interfacial interactions between PANI and the titanate phase, accompanied by structural reorganization of the titanate phase and the formation of Ti-O-C bonding environments. Morphological and elemental mapping confirm a well-integrated hybrid architecture in which PANI coats and interconnects the micrometric tubular oxide framework. Temperature-dependent electrical measurements show thermally activated semiconducting behavior for both materials, with increased activation energies and reduced carrier density in the composite—consistent with charge trapping and interfacial potential barriers introduced by the HTMT. Importantly, the PANI/HTMT hybrid exhibits a pronounced and reversible photoconductive response under blue and red LED illumination, whereas pristine PANI shows no measurable photoresponse. The effect is stronger under blue illumination and at intermediate cryogenic temperatures (75–200 K), indicating that photoexcitation in HTMT followed by interfacial charge transfer governs the conductivity modulation. These findings demonstrate that PANI/HTMT microstructured composites constitute a scalable, low-cost, and cryogenically compatible photoactive material.