Cs₂SnI₆-Encapsulated Multidye-Sensitized All-Solid-State Solar Cells

The design of a dye-sensitized solar cell (DSSC) based on the simultaneous incorporation of multiple dyes is examined. By investigating the use of the porphyrin-based YD2-o-C8 and YDD6, and the organic chromophore TTAR, which can act as complementary absorbers, we are able to enhance the capture of incoming light across the solar spectrum. This is demonstrated first by using a conventional DSSC architecture with a liquid electrolyte and performed a power conversion efficiency (PCE) of 11.2%, representing an improvement over cells based on each of the independent dyes. Next, we used Cs₂SnI₆ as an encapsulating layer over the sensitizing molecules to reduce charge leakage across the dye layers and also added to the absorption of longer wavelengths up to one micron. Finally, we fabricated a cell utilizing a Cs₂SnI₆/succinonitrile solid hole-transport electrolyte and achieved a PCE of ∼8.5%. It is expected that the all solid-state design will go a long way toward improving long-term device stability.