Iodine doped polyaniline thin film for heterostructure devices via PECVD technique: Morphological, structural, and electrical properties

Abstract

The deposition of undoped and iodine (I2)-doped polyaniline (PANI) on TiO2 thin film was carried out using plasma-enhanced chemical vapor deposition (PECVD) under different power inputs for the fabrication of p-polyaniline/n-TiO2 heterostructure devices. The increment in the size of TiO2 nanoparticles was observed after I2 doping by PECVD. The crystalline properties were altered upon I2 doping, suggesting a subtractive interaction between PANI and I2 moieties during PECVD. The significant changes in the structural and optical properties confirmed the I2 doping of PANI with strong bonding to the TiO2 nanomaterials. The existence of hydrogen bonding between the imine (-NH) of PANI and the hydroxyl (-OH) group of TiO2 nanomaterials was investigated by X-ray photoelectron spectroscopy characterization. A device fabricated by PANI/TiO2 or I2-PANI/TiO2 thin film with a top platinum (Pt) layer exhibited nonlinear behavior of current (I)-voltage (V) curve, i.e., moderate diode behavior. Compared to the Pt/PANI/TiO2 heterostructure device, the Pt/I2-PANI/TiO2 heterostructure device showed improved I–V properties with a considerably higher current of 0.050 mA, which might be attributed to the I2 doping-induced generation of large numbers of polarons in the PANI bandgap. Open image in new window