Influence of oxygen on semi-transparent organic solar cells with gas permeable electrodes

Semi-transparent P3HT:PCBM (poly(3-hexylthiophene):[6,6]-phenyl C61 butyric acid methyl ester) solar cells with high conductivity PEDOT:PSS (poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)) top electrodes are used to study degradation. Due to the gas permeability of this type of electrode, the simultaneous exposure to oxygen and light leads to a strong decrease of the short circuit current on the timescale of minutes. The losses are not due to a change in the conductivity of the PEDOT:PSS layer, and the short circuit current can be partially recovered by a heating step, indicating that the observed degradation is taking place in the photo-active layer of the cell.