Tungsten trioxide (WO3) is a paradigmatic electrochromic material, whose peculiar optical properties in the presence of oxygen vacancies or intercalated alkali atoms have been observed and investigated for a long time. In this paper we propose a rationalization of experiments based on first-principles calculations of optical and electrical properties of oxygen-deficient (reduced) WO3. Our approach is based on a parameter-free dielectric-dependent hybrid density functional methodology, used in combination with the charge transition levels formalism, for studying excitation mechanisms in the presence of defects. Our results indicate that oxygen vacancies lead to a different physics in γ-monoclinic WO3, depending on the orientation of the W-O-W chain where the vacancy is created, thus evidencing strong anisotropic effects rooted in the peculiar structural properties of the original nondefective monoclinic cell. Different types of oxygen vacancies can hence be classified on the basis of the calculated ground state properties, electronic structure, and excitation/emission energies, giving a satisfactory explanation to a range of experimental observations made on oxygen-deficient WO3.

Gerosa, M., DI VALENTIN, C., Onida, G., Bottani, C., Pacchioni, G. (2016). Anisotropic Effects of Oxygen Vacancies on Electrochromic Properties and Conductivity of γ-Monoclinic WO3. JOURNAL OF PHYSICAL CHEMISTRY. C, 120(21), 11716-11726 [10.1021/acs.jpcc.6b02707].

Anisotropic Effects of Oxygen Vacancies on Electrochromic Properties and Conductivity of γ-Monoclinic WO3

DI VALENTIN, CRISTIANA
Secondo
;
PACCHIONI, GIANFRANCO
Ultimo
2016

Abstract

Tungsten trioxide (WO3) is a paradigmatic electrochromic material, whose peculiar optical properties in the presence of oxygen vacancies or intercalated alkali atoms have been observed and investigated for a long time. In this paper we propose a rationalization of experiments based on first-principles calculations of optical and electrical properties of oxygen-deficient (reduced) WO3. Our approach is based on a parameter-free dielectric-dependent hybrid density functional methodology, used in combination with the charge transition levels formalism, for studying excitation mechanisms in the presence of defects. Our results indicate that oxygen vacancies lead to a different physics in γ-monoclinic WO3, depending on the orientation of the W-O-W chain where the vacancy is created, thus evidencing strong anisotropic effects rooted in the peculiar structural properties of the original nondefective monoclinic cell. Different types of oxygen vacancies can hence be classified on the basis of the calculated ground state properties, electronic structure, and excitation/emission energies, giving a satisfactory explanation to a range of experimental observations made on oxygen-deficient WO3.
Articolo in rivista - Articolo scientifico
Electronic, Optical and Magnetic Materials; Energy (all); Surfaces, Coatings and Films; Physical and Theoretical Chemistry
English
11716
11726
11
Gerosa, M., DI VALENTIN, C., Onida, G., Bottani, C., Pacchioni, G. (2016). Anisotropic Effects of Oxygen Vacancies on Electrochromic Properties and Conductivity of γ-Monoclinic WO3. JOURNAL OF PHYSICAL CHEMISTRY. C, 120(21), 11716-11726 [10.1021/acs.jpcc.6b02707].
Gerosa, M; DI VALENTIN, C; Onida, G; Bottani, C; Pacchioni, G
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/149935
Citazioni
  • Scopus 59
  • ???jsp.display-item.citation.isi??? 59
Social impact