The effect of plasmonic multilayered photoanode structures on the absorption of dye-sensitized solar cells

Dye-sensitized solar cells (DSSCs) have recently gained much attention, due to the low-cost materials and their cheaper manufacturing techniques. However, these cells show a weak response to incident solar photons, resulting in poor power-conversion efficiency. In this paper, we described an improvement to the optical absorption efficiency of DSSCs in the wavelength range between 350 nm and 750 nm using the surface plasmon-resonance effect of plasmonic nanoparticles. Three different structures are studied, including unilayer, bilayer, and trilayer photoanodes based on various core-shell plasmonic spherical nanoparticles made of Ag(a)TiO₂. In all structures, the nanoparticle size is optimized to obtain broadband optical absorption. The absorption efficiency of the dye-sensitized solar cell is significantly improved, from 65.2% to 72.3%, by tuning the photoanode structure from unilayer to trilayer. The results show that a unilayer photoanode with smaller-sized nanoparticles leads to higher absorption, compared to larger sizes. The UV-vis results indicate that mixing large- and small-sized nanoparticles in bi- and trilayer photoanodes is a good approach for improving the light-harvesting efficiency of DSSCs, compared to uniformly distributed nanoparticles. A maximum short-circuit current density of 17.32 mA cm⁻² is recorded for a photoanode based on a trilayer structure of Ag(a)TiO₂ nanoparticles. (author)