Employing a mol. dyad and a cobalt-based electrolyte gives a threefold-increase in open-circuit voltage (VOC) for a p-type NiO device (VOC=0.35 V), and a fourfold better energy conversion efficiency. Incorporating these improvements in a TiO2/NiO tandem dye-sensitized solar cell (TDSC), results in a TDSC with a VOC=0.91 V.