TY - JOUR
T1 - The influence of initial stoichiometry on the mechanism of photochromism of molybdenum oxide amorphous films
AU - Rouhani, Mehdi
AU - Hobley, Jonathan
AU - Subramanian, Gomathy Sandhya
AU - Phang, In Yee
AU - Foo, Yong Lim
AU - Gorelik, Sergey
N1 - Funding Information:
MR is grateful to SINGA for supporting his PhD program, SG, JH would like to acknowledge A⁎STAR-JST Strategic International Cooperative Programme (1st Joint Grant Call - project number 1021630071).
PY - 2014/7
Y1 - 2014/7
N2 - We investigate the role of oxygen vacancies in photochromism of molybdenum oxide amorphous films. MoO3-x films with a wide range of initial stoichiometries are deposited using R.F. unbalanced magnetron sputtering. The evolution of visible light absorption in conjunction with Raman spectra for these films is studied in detail during the course of UV-irradiation to correlate the color change to the Mo6+ to Mo5+ conversion. For films which have an initially more complete stoichiometry, and hence lower oxygen vacancy concentration, the color change fully correlates with conversion of Mo6+ to Mo5+. This behavior is consistent with the group of models of photochromism of transition metal oxides which disregard the presence of oxygen vacancies in the films. However, coloration of the films with initially greater deviation from complete stoichiometry, and hence higher oxygen vacancy concentration, is not accompanied by any significant conversion of Mo6+ to Mo5+. This behavior is consistent with the group of models of photochromism of transition metal oxides which rely on the presence of oxygen vacancies. Overall, the reported results demonstrate the importance of the initial stoichiometry in the photochromism of MoO 3-x amorphous films, particularly in the initial stages of UV-irradiation.
AB - We investigate the role of oxygen vacancies in photochromism of molybdenum oxide amorphous films. MoO3-x films with a wide range of initial stoichiometries are deposited using R.F. unbalanced magnetron sputtering. The evolution of visible light absorption in conjunction with Raman spectra for these films is studied in detail during the course of UV-irradiation to correlate the color change to the Mo6+ to Mo5+ conversion. For films which have an initially more complete stoichiometry, and hence lower oxygen vacancy concentration, the color change fully correlates with conversion of Mo6+ to Mo5+. This behavior is consistent with the group of models of photochromism of transition metal oxides which disregard the presence of oxygen vacancies in the films. However, coloration of the films with initially greater deviation from complete stoichiometry, and hence higher oxygen vacancy concentration, is not accompanied by any significant conversion of Mo6+ to Mo5+. This behavior is consistent with the group of models of photochromism of transition metal oxides which rely on the presence of oxygen vacancies. Overall, the reported results demonstrate the importance of the initial stoichiometry in the photochromism of MoO 3-x amorphous films, particularly in the initial stages of UV-irradiation.
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U2 - 10.1016/j.solmat.2014.03.033
DO - 10.1016/j.solmat.2014.03.033
M3 - Article
AN - SCOPUS:84897998552
VL - 126
SP - 26
EP - 35
JO - Solar Energy Materials and Solar Cells
JF - Solar Energy Materials and Solar Cells
SN - 0927-0248
ER -