Monitoring the reactivity of oxide interfaces in dye solar cells with photocurrent imaging techniques

By partially dip-coating and processing the F:SnO2 front contact so that a very thin layer of platinum or of ruthenium oxide is formed, a breakdown of solar cell efficiency is observed via photocurrent imaging techniques. This evidences that the front contact functions like a degenerate semiconductor which determines the cell photopotential. Modification of the TiO2 nanosurface with ultra thin alternative oxide layers (ZnO, Al2O3) affects both electron injection and reverse reaction and thus photoefficiency. ZnO- and Al2O3- modified TiO2 interfaces show an increased rate of sensitizer degradation. This result emphasizes the role of interfacial sensitizer bonding for long-term stability.