abstract
Mixed transition metal oxides, known for their superior electrochemical performance, are widely used in lithium batteries, supercapacitors, and other energy storage devices. In electrochromics, which have evolved from single to multifunctional applications, these oxides are particularly valuable. Integrating charge storage in electrochromic devices represents a promising advance in energy technology. In this study, transparent niobium-molybdenum oxides were deposited on rigid and flexible substrates by using DC magnetron sputtering. Samples were prepared with Mo/Nb atomic ratios up to 0.62, with a fixed O2/Ar flow ratio of 0.52 and a 15 min deposition time. Film thickness ranged from 195 nm (0 Mo) to 620 nm (0.62 Mo), displaying a featureless and amorphous morphology. Surface roughness (Sq) was on the nanometric scale, reaching a maximum of 18 nm. Optical transmission in the visible range was up to 82% for Mo-free films. Dielectric response increased with molybdenum content, peaking at epsilon' = 294 (dielectric constant) at 300 K and 1 kHz for the 0.62 Mo sample. Films on flexible substrates showed improved mechanical durability in the bending tests. The electrochromic behavior was evaluated under Li+ intercalation, demonstrating strong reversibility and reproducibility, achieving a maximum coloration efficiency of 30.49 cm2/C, a maximum reversibility of 83%, and a relative optical modulation of up to 79%.
keywords
MIXED-METAL OXIDES; RAMAN-SPECTRA; ELECTROCHROMIC PROPERTIES; BAND-GAP; MOO3; MODULATION; COLORATION
subject category
Chemistry; Energy & Fuels; Materials Science
authors
Marciel, A; Bastos, AC; Pereira, L; Jakka, SK; Borges, J; Vaz, F; Peres, M; Lorenz, K; Alves, LC; Bafti, A; Pavic, L; Silva, RF; Graça, M
our authors
Alice Maria da Costa Marciel Trabulo
PhD Student
António Alexandre Cunha Bastos
Assistant Researcher
Rui Ramos Ferreira e Silva
Associate ProfessorProjects
CICECO - Aveiro Institute of Materials (UIDB/50011/2020)
CICECO - Aveiro Institute of Materials (UIDP/50011/2020)
Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)
acknowledgements
The authors acknowledge the support from CICECO-Aveiro Institute of Materials UIDB/50011/2020 (DOI 10.54499/UIDB/50011/2020), UIDP/50011/2020 (DOI 10.54499/UIDP/50011/2020), and LA/P/0006/2020 (DOI 10.54499/LA/P/0006/2020), via FCT/MCTES (PIDDAC), i3N UIDB/50025/2020, UIDP/50025/2020, and LA/P/0037/2020 projects, as well as LISBOA-01-0247 FEDER-039985/POCI-01-0247-FEDER-039985 projects, and C2TN UID/Multi/04349/2020 (DOI: 10.54499/UIDB/04349/2020). Authors also acknowledge the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UIDB/04650/2020 (CF-UM-UP research unit). Joel Borges acknowledges FCT for his research contract funding, reference CEECINST/00156/2018/CP1642/CT0001.