Charge Transport and Recombination in Dye-Sensitized Solar Cells on Plastic Substrates

Abstract

Dye-sensitized solar cells (DSSCs) formed on plastic substrates boast immense potential for commercialization; however, plastic substrate DSSCs have only achieved efficiencies approximately half that of their glass substrate counterparts. Previous work has largely attributed these medial efficiencies to the inability to sinter the mesoporous TiO2 film. This study entailed the comparison of high-temperature and low-temperature fabricated DSSCs, moving beyond comparisons of device efficiencies and quantitatively characterizing the physical mechanisms underpinning the gap between plastic and glass technologies. As shown through small perturbation techniques, the dominance of sintered working electrodes was reflected in their superior electron diffusion lengths, which were approximately three-to-four times greater than the nonsintered films. The improved performance gained after a TiO2 nanoglue treatment was also investigated and was observed to be caused by a reduction in charge recombination dynamics and a modest improvement in electron diffusion rates. These findings present significant impacts for the benchmark methods currently used to fabricate plastic substrate DSSCs, illustrating the divide that needs to be bridged between low-temperature and high-temperature fabrication techniques.