Nb- or Ta-doped anatase TiO2 was shown to be a viable candidate for replacing indium-tin-oxide as a transparent conductive oxide. Calculating the electronic structures we find that Ta has the considerably higher solubility and lower optical effective mass of the two dopants. Our calculations also show that a reducing atmosphere is necessary for efficient dopant incorporation, and oxygen vacancies do not necessarily play a role in their activation.
REFERENCES
The error in the calculated heats of formation can vary just as well as that of the gap between various wide band gap oxides. HSE06 happens to reproduce both very accurately in TiO2.20 The heat of formation for anatase was calculated to be −9.68 eV, within ∼1% of the experimental value, −9.78 eV. Since the error is considerably bigger in the pentoxides, we use the experimental heat of formation for those.
We note that the heat of formation for Nb2O5 is lower than for Ta2O5 by 1.5 eV. Therefore, the lower formation energy of TaTi stems from the interaction with the TiO2 environment.
