Deepa, M and Singh, P. and Sharma, S. N. and Agnihotry, S. A. (2006) Effect of humidity on structure and electrochromic properties of sol-gel-derived tungsten oxide films. Solar Energy Materials and Solar Cells, 90 (16). pp. 2665-2682. ISSN 0927-0248

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Abstract

The influence of varying relative humidity (RH similar to 55 and 75%) during thin film deposition from an oxalato-acetylated peroxotungstic acid sol by dip coating, on the microstructure and electrochromic properties of pristine tungsten oxide (WO3) films obtained upon annealing is presented. The films fabricated under a relative humidity of 55% are amorphous whereas the ones cast under a substantially humid atmosphere (RH similar to 75%) are characterized by interconnected nanocrystallites with a triclinic phase and a nanoporous surface morphology as well. Upon lithium insertion, larger integrated values of transmission modulation and coloration efficiency are observed over the photopic and solar regions, for the films prepared under a RH-75% as compared to that observed for the films deposited under a RH of 55%. Functional improvements are due to the larger surface area of nanocrystallites and a porous microstructure, a consequence of a higher degree of hydration and hydroxylation in the former films in contrast to the non-porous and a rather featureless structure of the latter films. Faster switching kinetics between the clear and blue states, a greater current density for lithium intercalation, a higher diffusion coefficient for lithium and a superior cycling stability, again shown by the film fabricated under a 75% RH confirm that the WO3 film microstructure is most conducive for a more facile ion insertion-extraction process, which hints at its potential for electrochromic window applications.

Item Type:	Article
Additional Information:	Copyright for this article belongs to M/s Elsevier.
Subjects:	Energy Fuels Materials Science Applied Physics/Condensed Matter
Divisions:	UNSPECIFIED
Depositing User:	Users 27 not found.
Date Deposited:	09 May 2018 08:54
Last Modified:	25 Feb 2019 11:40
URI:	http://npl.csircentral.net/id/eprint/2458

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