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The mechanism of charge transport in polypyrrole (PPy) nanoparticles prepared with different concentrations (5 to 30 mM) of anionic surfactant (sodium dodecyl sulfate) is reported. Transmission electron microscopy technique confirms the formation of PPy nanoparticles of sizes ∼52 to 28 nm under surfactant directed approach. The room temperature electrical conductivity of the prepared nanoparticles found to increase from 3 to 22 S/cm with surfactant concentration. The temperature dependent activation energy rules out the possibility of band conduction mechanism in the prepared PPy nanoparticles and thus the synthesized nanoparticles are analyzed under variable range hopping (VRH) model for conduction mechanism. The PPy nanoparticles, reduced with liquid ammonia, hold 3D VRH conduction mechanism for the charge transport. However, in the doped samples, some deviation from 3D VRH conduction behavior at higher temperatures (>150 K) has been observed. This may be attributed to the presence of anionic surfactant in these samples. The doping of anionic surfactant causes rise in conducting islands, which may lead to the change in the shape/distribution of density of states governed by Gaussian or exponential type near Fermi level.

A surfactant assisted facial hydrothermal process has been employed for the synthesis of rutile and wurztile phase SnO 2 and ZnO nanoparticles, respectively, confirmed by X-ray diffraction studies. High resolution transmission electron microscopy studies revealed the formation of ~15 and 20 nm of SnO 2 and ZnO nanoparticles, respectively, whereas, the structural analysis was done via Fourier transform infrared (FTIR) and Raman spectroscopy studies that suggested the minor doping of surfactant and surface adsorption of environmental oxygen. The gas sensing behavior of the prepared nanoparticles has been measured in ammonia environment and the sensing responses of the SnO 2 and ZnO nanoparticles are found to be 4.53 and 3.96% at 46 ppm of ammonia. The mechanism of interaction of ammonia with metal oxide nanoparticles has been investigated through FTIR and Raman spectroscopic measurements performed in ammonia environment.

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The current research aims to investigate the effect of nickel doping on the structural and opto-electrical characteristics of zinc oxide thin films. Sol-gel spin coating technique has been utilized to deposit Zn1-xNixO (x=0, 0.005, 0.010, and 0.015) films on glass substrates. X-ray diffraction (XRD) analysis confirms the formation of crystalline zinc oxide thin films with hexagonal wurtzite structure. Williamson-Hall analysis has been performed to study the individual contribution of lattice strain and crystallite size to the peak broadening in the XRD pattern. Scanning electron microscopy (SEM) and UV-Visible spectroscopic techniques have been used to examine the surface morphology and optical properties of the deposited films. Transient photocurrent measurements have been performed on all the films under the exposure of ultraviolet (UV) light of wavelengths 365 and 254 nm with on/off cycle of 100 seconds, and various device key parameters such as sensitivity, responsivity and quantum efficiency, etc. have been determined. Sensitivities of the fabricated photodetectors (PDs) are found to be 5463%, 3809%, 3100%, and 831% for pristine ZnO, Zn0.995Ni0.005O, Zn0.99Ni0.01O, and Zn0.985Ni0.015O, respectively. The UV photodetection mechanism, which is based on the interaction between chemisorbed oxygen on the surface of ZnO and photo-generated holes, has been thoroughly discussed.

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