Combinatorial Investigation and Modelling of MoO3 Hole-Selective Contact in TiO2|Co3O4|MoO3 All-Oxide Solar Cells

A TiO2 vertical bar Co3O4 vertical bar MoO3 all-oxide solar cell produced by spray pyrolysis and pulsed laser deposition (PLD) onto a fluorine-doped tin-oxide (FTO) glass substrate with gold (Au) back contacts is demonstrated for the first time. A combinatorial approach is implemented to study the effect of molybdenum oxide (MoO3) as a recombination contact and the influence of the cobalt oxide (Co3O4) light-absorber thickness on the performance of the solar cells. An increase of more than 200 mV in the open circuit voltage (V-oc) is observed with a concurrent enhancement in terms of short-circuit current (J(sc)) and maximum power in comparison with TiO2 vertical bar Co3O4 devices without the MoO3 layer. To understand the mechanism, full drift diffusion simulations are performed. The higher performance is attributed to elimination of a recombination process at the absorber/metal back-contact interface and surface passivation by the MoO3 layer.