Preparation and Properties of Spin-Coated Nb2O5 Films by the Sol-Gel Process for Electrochemical Applications
Title | Preparation and Properties of Spin-Coated Nb2O5 Films by the Sol-Gel Process for Electrochemical Applications |
Publication Type | Journal Article |
Year of Publication | 1995 |
Authors | Nilgün Özer, Din-Guo Chen, Carl M Lampert |
Journal | Thin Solid Films |
Volume | 277 |
Start Page | 162 |
Issue | 1-2 |
Pagination | 162-168 |
Date Published | 05/1996 |
Call Number | LBNL-39008 |
Keywords | Electrochemistry, Niobium oxide, optical properties, X-ray photoelectron spectroscopy |
Abstract | The preparation and properties of Nb2O5 coatings made by the sol-gel process were investigated. The films were deposited by spin coating on In2O3:Sn/glass and quartz substrates from a polymeric solutions of niobia derived from niobium ethoxide. The films were characterized by investigation of the stoichiometry, refractive index, optical transmission, electrochemical behavior, and the microstructure. X-ray diffraction studies showed the films to be amorphous for heat treatments below 450 °C. X-ray photoelectron spectroscopy (XPS) measurement revealed the O:Nb atomic stoichiometry to be 5:2. Cyclic voltammetric measurements showed that the Nb2O5/1 M LiClO4-propylene carbonate system exhibits electrochemical reversibility beyond 1200 cycles without change in performance. In situ UV-Vis-NIR spectroelectrochemical measurement revealed that Nb2O5 films exhibit an electrochromic effect in the spectral range 300<λ<2100 nm and remain unchanged in the infrared spectral range. The change in visible transmittance was 40% for a 250 nm thick electrode. XPS spectra indicate that Nb(V) is reduced to a lower valence state Nb(IV) in a colored state with injected Li+. The bronze coloration is due to a simultaneous injection of electrons and Li+ ions into Nb2O5. The sol-gel-deposited Nb2O5 films are useful for cathodically coloring electrochromic electrodes in electrochromic devices. |
URL | http://dx.doi.org/10.1016/0040-6090(95)08011-2 |
LBNL Report Number | LBNL-39008 |