Indium-free multilayer semi-transparent electrodes for polymer solar cells

We have explored the fabrication of indium-free electrodes for use in a PCDTBT:PC70BM organic photovoltaic (OPV) device, and compare different multilayer electrodes as the device anode. Two oxide/metal/oxide structures were investigated that consisted of MoO3/Ag/MoO3 (MAM) and TeO2/Ag/MoO3 (TAM) multilayers. Using scanning electron microscopy measurements, we find that the electrode utilising a TeO2 seed layer encouraged the growth of a more continuous silver layer at low film thickness relative to an MoO3 seed layer, and thus combines enhanced optical transmission (by around 7%) with low sheet resistance (14 Ω/□). This enhanced optical transmittance results in an increased short-circuit current in photovoltaic cells, with TAM-based devices having a power conversion efficiency around 6% higher than those fabricated using a comparable MAM electrode.