Electrochromic properties of hydrothermally grown microstructured V 2 O 5 and MWCNT/V 2 O 5 composite films

Vanadium pentoxide (V 2 O 5 ) and multiwalled carbon nanotubes added V 2 O 5 composite (MWCNT/V 2 O 5 ) films were prepared by hydrothermal technique. The influence of various levels of MWCNT on the electrochromic properties of MWCNT/V 2 O 5 films was investigated. X-ray diffraction analysis revealed that the films are polycrystalline in nature and belong to orthorhombic crystal system of V 2 O 5 . Raman and FTIR spectral analyses confirmed the formation of V 2 O 5 phase and the influence of MWCNT on the vibrational frequencies of V 2 O 5 films. V 2 O 5 film added with 1 wt.% MWCNT showed enhanced transmittance and the bandgap of V 2 O 5 increases with further increase in the addition of MWCNT in V 2 O 5 films. The electrochromic studies revealed electrochromic reversibility of 82% (1 wt.% MWCNT added film) and 82.5% (5 wt.% MWCNT added film) whereas after 100 cycles the films added with 1 wt.% and 5 wt.% of MWCNT acquired excellent electrochromic reversibility of 92% and 88%, respectively. Further the switching kinetics of the film added with 1 wt.% MWCNT is 1.8 s for coloration and 2.4 s for bleaching processes.