Solar Energy, Vol.208, 747-752, 2020
Photon management strategies in SSM-DSCs: Realization of a > 11% PCE device with a 2.3 V output
A sequential series multijunction dye-sensitized solar cell (SSM-DSC) designed to minimize optical and free energy losses to enable higher device performance is reported. Efficient photon management of solar spectrum irradiation was made possible by: controlling TiO2 film thickness in each subcell leading to balanced photocurrent, careful sensitizer selection based on absorption breadth and intensity for each subcell, and minimizing photon losses by application of an anti-reflective coating with an immersion oil between subcells. By using these strategies with a deep NIR absorbing sensitizer, an SSM-DSC device based on D35/B11/Black Dye demonstrated an overall power conversion efficiency of >11% with a photovoltage of 2.3 V from a single illuminated area device. The PCE of the SSM-DSC is significantly higher than any of the individual subcell in the mechanical stack. This approach has led to a higher performing device than the prior reported high efficiency SSM-DSC devices based on D35/B11/B11 or the all organic dye SSM-DSC based on D35/MK2/AP25 + D35.