Inherent electronic trap states in TiO2 nanocrystals: effect of saturation and sintering (Articolo in rivista)

Type
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  • Inherent electronic trap states in TiO2 nanocrystals: effect of saturation and sintering (Articolo in rivista) (literal)
Anno
  • 2013-01-01T00:00:00+01:00 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#doi
  • 10.1039/c3ee24100a (literal)
Alternative label
  • Francesca Nunzi, Edoardo Mosconi, Loriano Storchi, Enrico Ronca, Annabella Selloni, Michael Graetzel, Filippo De Angelis (2013)
    Inherent electronic trap states in TiO2 nanocrystals: effect of saturation and sintering
    in Energy & environmental science (Print)
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • Francesca Nunzi, Edoardo Mosconi, Loriano Storchi, Enrico Ronca, Annabella Selloni, Michael Graetzel, Filippo De Angelis (literal)
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  • 1221 (literal)
Pagina fine
  • 1229 (literal)
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  • http://pubs.rsc.org/en/content/articlelanding/2013/EE/C3EE24100A (literal)
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  • 6 (literal)
Rivista
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  • 9 (literal)
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  • 4 (literal)
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  • Francesca Nunzi, Edoardo Mosconi, Enrico Ronca, Filippo De Angelis: a Computational Laboratory of Hybrid/Organic Photovoltaics (CLHYO), Istituto CNR di Scienze e Tecnologie Molecolari, via Elce di Sotto 8, I-06123 Perugia, Italy. E-mail: ?lippo@thch.unipg.it; Fax: +39 075 5855606; Tel: +39 075 5855523 Francesca Nunzi, Enrico Ronca:Dipartimento di Chimica, Universita degli Studi di Perugia, via Elce di Sotto 8, I- ` 06123 Perugia, Italy. E-mail: nunzi@thch.unipg.it; Fax: +39 075 5855606; Tel: +39 075 5855517 Loriano Storchi:Dipartimento di Farmacia, Universita G. D'Annunzio, via dei Vestini 31, 66100 Chieti, ` Italy Annabella Selloni: Department of Chemistry Princeton University New Jersey 08544 United States Michael Graetzel: Laboratory for Photonics and Interfaces Station 6 Institute of Chemical Sciences and Engineering School of Basic Sciences Swiss Federal Institute of Technology CH-1015 Lausanne Switzerland (literal)
Titolo
  • Inherent electronic trap states in TiO2 nanocrystals: effect of saturation and sintering (literal)
Abstract
  • We report a quantum mechanical investigation on the nature of electronic trap states in realistic models of individual and sintered anatase TiO2 nanocrystals (NCs) of ca. 3 nm diameter. We find unoccupied electronic states of lowest energy to be localized within the central part of the NCs, and to originate from under-coordinated surface Ti atoms lying mainly at the edges between the (100) and (101) facets. These localized states are found at about 0.3-0.4 eV below the fully delocalized conduction band states, in good agreement with both electrochemical and spectro-electrochemical results. The overall DensityOf-States (DOS) below the conduction band (CB) can be accurately fitted to an exponential distribution of states, in agreement with capacitance data. Water molecules adsorbed on the NC surface raise the energy and reduce the number of localized states, thus modifying the DOS. As a possible origin of additional trap states, we further investigated the oriented attachment of two TiO2 NCs at various possible interfaces. For the considered models, we found only minor differences between the DOS of two interacting NCs and those of the individual constituent NCs. Our results point at the presence of inherent trap states even in perfectly stoichiometric and crystalline TiO2 NCs due to the unavoidable presence of under-coordinated surface Ti(IV) ions at the (100) facets (literal)
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