OICC Press International Nano Letters 2228-5326 3 1 (December 2013) 2013 04 17 Spectroscopic and electrochromic properties of activated reactive evaporated nano-crystalline V2O5 thin films grown on flexible substrates 10.1186/2228-5326-3-24 EN Hari Krishna Koduru CNR-IPCF UoS di Cosenza, Licryl Laboratory, and Centro di Eccellenza CEMIF.CAL, Università della Calabria, Rende (Cosenza), 87036, IT Hussain Mahammad Obili Thin film Laboratory, Department of Physics, Sri Venkateswara University, Tirupati, 517 502, IN Guillèn Cecilia Department of Energy, CIEMAT, Madrid, 28040, ES Journal Article 2013 04 17 Abstract Vanadium pentoxide (V 2 O 5 ) thin films were grown on indium tin oxide-coated flexible Kapton substrates by home-built activated reactive evaporation technique. Film depositions were carried out at optimised oxygen partial pressure of 1 × 10 −3 Torr and plasma power of 8 W, and we investigated their microstructural and opto-electrochromic properties as a function of substrate temperature. The V 2 O 5 films grown at T s = 473 K exhibited a nano-crystalline nature as evidenced from X-ray diffraction, atomic force microscopy and Raman studies. The nano-crystalline films composed of vertical elliptical-shaped grainy morphology demonstrated a high optical transmittance of 75% with an estimated optical bandgap of 2.38 eV. The dry lithiated nano-crystalline V 2 O 5 films demonstrated an optical modulation of 36.1% with a coloration efficiency value of 26.2 cm 2 /C at a wavelength of 550 nm. As-deposited nano-crystalline V 2 O 5 thin films demonstrated a constant discharge capacity of about 60 μAh cm −2 μm −1 for a few cycles at room temperature in the potential window of 4.0 to 2.5 V.