Effect of electron collecting metal oxide layer in normal and inverted structure polymer solar cells

We performed a systematic study of the effect of electron collecting metal oxide layer on the performance of P3HT: PCBM solar cells. Zinc oxide (ZnO) or titanium dioxide (TiO2) buffer layers were prepared by either e-beam evaporation or solution processing method. We also compared the photovoltaic performance of inserting the buffer layer between indium tin oxide (ITO) and the polymer layer for the inverted structure (ITO/ ZnO or TiO2/P3HT:PCBM/V2O5/Au) as well as inserting the buffers layers between the polymer and the aluminum electrode for the conventional structure (ITO/V2O5/P3HT:PCBM/ZnO or TiO2/Al). The results are shown in detail.