01932nas a2200169 4500008004100000050001400041245009300055210006900148300001200217490000700229520136600236100001901602700002101621700002301642700002101665856007601686 1994 eng d aLBL-3852500aCharacterization of Sol-Gel Deposited Niobium Pentoxide Films for Electrochromic Devices0 aCharacterization of SolGel Deposited Niobium Pentoxide Films for a433-4430 v363 a

Niobium pentoxide films, fabricated by the sol-gel process, were spin coated onto conductive indium tin oxide (ITO)/glass, and microscope slides. These films were cycled in a 1M LiClO4 propylene carbonate (PC) solution, and exhibited electrochromic behavior upon the electrochemical insertion (reduction) and extraction (oxidation) of lithium. In-situ optical transmittance measurements were investigated in the ultraviolet/visible/near-infrared wavelength regions (250-2100 nm). Niobium pentoxide films showed reversible optical switching from 320 to 870 nm, but were found electrochromically inactive in the infrared region. Surface analysis using X-ray photoelectron spectroscopy (XPS) indicated little difference in the chemistry of Nb2O5 films as deposited and lithiated LixNb2O5 films, as XPS binding energies of Nb and O showed no appreciable shifts. These films were found to be amorphous by X-ray diffraction. Optical transmittance measurements combined with cyclic voltamograms and XPS spectra, revealed that the electrochromic behavior of these films occurs due to the insertion of Li+ cations into niobium pentoxide films. The bronze coloration of the niobium pentoxide films could make them useful as an electrochromic counter electrodesfor electrochromic devices.

1 aÖzer, Nilgün1 aBarreto, Timothy1 aBuyuklimanl, Temel1 aLampert, Carl, M uhttps://facades.lbl.gov/publications/characterization-sol-gel-deposited01431nas a2200133 4500008004100000050001500041245010100056210006900157520093400226100001901160700001801179700002101197856007901218 1994 eng d aLBNL-3900500aCharacterization of Tantalum Oxide Films Prepared by Sol-Gel Process for electrochemical devices0 aCharacterization of Tantalum Oxide Films Prepared by SolGel Proc3 a

Tantalum oxide films were prepared by sol-gel process using tantalum ethoxide Ta(OC2H5)5. The dependence of deposition conditions (i.e. composition of polymeric solutions and spinning rate) on ionic conductivities for tantalum oxide films were studied. The best results achieved for films fabricated by the spin coating technique were from clear polymeric solutions. These films had low packing density ρ=3.2 g/cm3 and good proton conductivity (about 10-6 Ω-1 cm-1). X-ray photoelectron spectroscopy (XPS) was used for studying the compositions of the tantalum oxide films. We report on the use of tantalum oxide films as ion conductors in devices consisting of WO3/Ta2O5/H+ ion storage polymer structure. We found tantalum oxide to have very good properties for proton device applications.

1 aÖzer, Nilgün1 aHe, Yongxiang1 aLampert, Carl, M uhttps://facades.lbl.gov/publications/characterization-tantalum-oxide-films