46
Figure 5.2: Bandgaps of few selected materials calculated with different methods
versus the GLLB-SC calculated bandgaps. The figure is taken from the
Paper-3.
5.4 Candidates for photoelectrochemical water
splitting
A few crucial properties a material should have for an efficient absorption of
light for photoelectrochemical water splitting are:
• Bandgap in the range of visible spectrum because the solar spectrum is
dominated by the visible light.
• Proper band edge positions in order to straddle the redox levels of water
in order to have the generated electron and hole at the right chemical
potential to carry out the reaction.
• Stability of the compound in water because the reaction takes place in
an aqueous medium.
Apart from the above mentioned properties, good electron-hole mobility, low
recombination rates etc. are also required for greater efficiency. However, modeling
of transport processes, recombination, defect centers etc. is much more
complicated therefore not considered here for an initial stage of the screening.