From evaporation to solution processed organic tandem solar cells

In this study, we have investigated the possibility to realize different types of stacked, serially connected organic solar cells. First of all, we combined solution processed MDMO-PPV:PCBM or P3HT:PCBM and evaporated ZnPc-C60 bulk-heterojunction solar cells to achieved tandem cells exploiting the complementary absorption spectra of each single cells. Such devices exhibit open circuit voltages of 1V with a short-circuit current of approximately 5mA/cm 2 and a fill factor of 0.35 under simulated AM1.5 illumination. In the case of stacked, series connected cells with all active layers processed from solution, we observed a significant increase of the open circuit voltage in comparison with the single junction cells: Device fabricated from two bilayers comprising MDMO-PPV and PCBM as photoactive materials exhibit 1.28V open circuit voltage, 1.1mA/cm 2 short circuit current and a fill factor of 0.45 under simulated AM1.5 illumination.