Kinetic behavior of WO3-doped Nb2O5 thin films

Luciana O. Melo; Douglas C. Dragunski; Cesar O. Avellaneda; Agnieszka Pawlicka

doi:10.1117/12.500985

25 July 2003 Kinetic behavior of WO₃-doped Nb₂O₅ electrochromic thin films

Luciana O. Melo, Douglas C. Dragunski, Cesar O. Avellaneda, Agnieszka Pawlicka

Proceedings Volume 4986, Physics and Simulation of Optoelectronic Devices XI; (2003) https://doi.org/10.1117/12.500985
Event: Integrated Optoelectronics Devices, 2003, San Jose, CA, United States

Abstract

An electrochromic material (EC) reversibly changes its optical characteristics response, coloring and bleaching states when a small voltage or current is passed through it. This phenomenon is used to develop electrochromic devices like smart windows, which control the amount of heat and light entering in a building and optimize energy consumption. The change of the transparency of these devices involves the injection and extraction of small cations and electrons into the EC material and study of the kinetics of ions injection implies on operation understanding of these devices. Pure and doped niobium oxides (Nb₂O₅) are promising cathodic electrochromic materials and their electrooptical performance depends strongly of its structural morphology. The sol-gel process allows for facile fabrication of large area coatings at a low cost and offers advantages of controlling the composition and microstructure of the films. In order to study the solid sate diffusion of lithium into Nb₂O₅, Nb₂O₅:Li⁺and Nb₂O₅:WO₃, two electroanalytical techniques have been used i.e. galvanostatic intermittent titration technique (GITT) and electrochemical impedance spectroscopy (EIS). GITT have been applied in order to obtain the chemical diffusion coefficient of Lix in Nb₂O₅ doped and undoped films, where the values approaching were of the 2.5x10^-11 cm²s^-1 at x=0,83, 7.4x10^-13 cm²s^-1 at x=1.65 and 1.6x10^-10 cm²s^-1 at x=0.33 for Nb₂O₅, Nb₂O₅:Li⁺ and Nb₂O₅-WO₃ respectively. From these measurements it was also observed that within each film, D increases as x increases.

Citation Download Citation

Luciana O. Melo, Douglas C. Dragunski, Cesar O. Avellaneda, and Agnieszka Pawlicka "Kinetic behavior of WO₃-doped Nb₂O₅ electrochromic thin films", Proc. SPIE 4986, Physics and Simulation of Optoelectronic Devices XI, (25 July 2003); https://doi.org/10.1117/12.500985

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