Volume 126 (2018) Issue 3 Pages 139-151
Demand for low-cost, environmentally friendly alternative renewable energy sources makes the dye-sensitized solar cell (DSSC) a viable alternative. DSSCs have a high but competitively challenged power conversion efficiency (PCE) of 11.9%. Plasmonic DSSCs is one approach with extreme enhancement of light absorption to increasing the PCE. The highest PCE of plasmonic DSSCs is still <11% however, due to secondary effects which are not yet well understood. In this study, we used a complex composite of plasmonic nanoparticles (PNPs) with extended characterization and wide ranging PNP loadings, combined with a systematic approach to obtain synergistic effects and a deeper understanding of the effects of plasmonic nanostructures on DSSC performance. The results showed two optimal loading amounts of PNPs with enhanced PCEs of 4.26 and 4.36% (from 3.54%), with enhancement effects obtained mainly from efficient charge injection and a balance of the negative and positive effects of the PNPs, respectively. An increase in the photoanode thickness from 5.5 to 9 µm resulted in PCE enhancement from 4.39 to 4.58%, mainly via efficient charge injection. The PNPs had both positive and negative effects on key DSSC performance parameters: decreased photoanode surface area but with panchromatic enhancement of light absorbance; increased short circuit current up to a point followed by a decrease due to poor charge injection; increased open circuit voltage and fill factor; enhanced charge transfer resistance against charge recombination; improved electron lifetime and charge collection efficiency; lowered enhancement of cell performance in the near infra-red region; and induced abundantly generated electrons augmented charge recombination. These results contribute significantly to understanding of the effects of plasmonic nanostructures and can serve as a useful guide to the study of plasmonic DSSCs and related fields.