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Solution Processing Route to Multifunctional Titania Thin Films: Highly Conductive and Photcatalytically Active Nb:TiO 2
Author(s) -
Bhachu Davinder S.,
Sathasivam Sanjayan,
Sankar Gopinathan,
Scanlon David O.,
Cibin Giannantonio,
Carmalt Claire J.,
Parkin Ivan P.,
Watson Graeme W.,
Bawaked Salem M.,
Obaid Abdullah Y.,
AlThabaiti Shaeel,
Basahel Sulaiman N.
Publication year - 2014
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201400338
Subject(s) - materials science , doping , sheet resistance , transparent conducting film , dopant , anatase , thin film , chemical vapor deposition , photocatalysis , titanium dioxide , chemical engineering , niobium , conductivity , nanotechnology , optoelectronics , layer (electronics) , composite material , metallurgy , chemistry , organic chemistry , engineering , catalysis
This paper reports the synthesis of highly conductive niobium doped titanium dioxide (Nb:TiO 2 ) films from the decomposition of Ti(OEt) 4 with dopant quantities of Nb(OEt) 5 by aerosol‐assisted chemical vapor deposition (AACVD). Doping Nb into the Ti sites results in n ‐type conductivity, as determined by Hall effect measurements. The doped films display significantly improved electrical properties compared to pristine TiO 2 films. For 5 at.% Nb in the films, the charge carrier concentration was 2 × 10 21 cm −3 with a mobility of 2 cm 2 V –1 s –1 . The corresponding sheet resistance is as low as 6.5 Ω sq –1 making the films suitable candidates for transparent conducting oxide (TCO) materials. This is, to the best of our knowledge, the lowest reported sheet resistance for Nb:TiO 2 films synthesized by vapour deposition. The doped films are also blue in colour, with the intensity dependent on the Nb concentration in the films. A combination of synchrotron, laboratory and theoretical techniques confirmed niobium doping into the anatase TiO 2 lattice. Computational methods also confirmed experimental results of both delocalized (Ti 4+ ) and localized polaronic states (Ti 3+ ) states. Additionally, the doped films also functioned as photocatalysts. Thus, Nb:TiO 2 combines four functional properties (photocatalysis, electrical conductivity, optical transparency and blue colouration) within the same layer, making it a promising alternative to conventional TCO materials.