Tuning the optical bandgap of V2O5 nanoparticles by doping transition metal ions

Abstract

Abstract In this study the influence of transition metal ions doping on optical properties of V2O5 nanoparticles is investigated. The shift in absorption edge caused by the dopant is analyzed from the UV-visible absorption spectra. The absorption edge of Ti doped V2O5 nanocrystals is shifted to longer wavelength region, while that of Zr doped V2O5 showed a blue shift. Ti doped V2O5 nanocrystal in spite of its large crystallite size showed improved optical properties and its optical bandgap (1.96 eV) is less than un-doped V2O5 (2.2 eV). This is attributed to lattice expansion by Ti ion and formation of oxygen vacancies within the bandgap. The oxygen vacancies acts as intermediate energy states and reduce the optical bandgap. However, the PL spectra of Ti-doped V2O5 did not exhibited emission peak corresponding to oxygen vacancies due to high crystallinity. The life time of excitons in excited state is investigated from time resolved PL decay. The excitons in doped sample showed tri-exponential decay whereas in pure sample they exhibited bi-exponential decay. The average lifetime of excitons in doped V2O5 is higher than pure V2O5 sample. This study reveals that by optimizing the concentration of Ti and Zr dopant ions in V2O5 lattice, its energy band structure can be tailored for photovoltaic, catalytic and photoluminescence applications. © 2018 Elsevier Ltd. All rights reserved. Selection and/or Peer-review under responsibility of International Conference on Nanotechnology: Ideas, Innovations & Initiatives-2017 (ICN:3i-2017).