Comparative study of electrical parameters and Li-ion storage capacity of PEG modified β-V2O5:M (M: Mo, Ni) thin films

Abstract

We report the comparative investigation of Mo and Ni incorporation effects on the electrochemical behavior, DC conductivity and optical transmittance of PEG/β-V2O5 thin films. Mo doping, changed the preferred orientation of tetragonal structure from (241) to (200) direction, while Ni doping had no considerable effect on the texture coefficient of pristine V2O5. Moreover, the highest electrical conductivity observed in PEG/V2O5:Mo sample could be related to the substitution of V5+ by Mo6+. This substitution increased electrical carrier concentration (3.7E19 cm−3) which led to the enhancement of electrical conductivity. Because of that, a significant improvement has been occurred in the electrochemical behavior of PEG/V2O5:Mo film. According to the results, the specific capacitance and the charge transfer resistance of PEG/V2O5:Mo thin films were found to be almost 5 times higher and less than half of pure V2O5 film, respectively. In addition, FESEM images showed that PEG/V2O5:Ni sample had nanoflaked surface morphology with dispersed nanograins, whereas the PEG/V2O5:Mo sample exhibited a special porous morphology with stacked nanograins distributed on striped sheets. Based on optical measurements, Mo doping also boosts the average transmittance of the PEG/V2O5 sample. Besides, the observed blue shift in the absorption edge of the doped samples could be attributed to the Burstein-Moss effect.