Journal article

Highly Efficient Solid-State Dye-Sensitized Solar Cells Based on Triphenylamine Dyes

Two triphenylamine-based metal-free org. sensitizers, D35 with a single anchor group and M14 with two anchor groups, were applied in dye-sensitized solar cells (DSCs) with a solid hole transporting material or liq. iodide/triiodide based electrolyte. Using the mol. hole conductor 2,2',7,7'-tetrakis-(N,N-di-p-methoxyphenyl-amine)9,9'-spirobifluorene (spiro-OMeTAD), good overall conversion efficiencies of 4.5% for D35 and 4.4% for M14 were obtained under std. AM 1.5G illumination (100 mW cm-2). Although M14 has a higher molar extinction coeff. (by ∼ 60%) and a slightly broader absorption spectrum compared to D35, the latter performs slightly better due to longer lifetime of electrons in the TiO2, which can be attributed to differences in the mol. structure. In iodide/triiodide electrolyte-based DSCs, D35 outperforms M14 to a much greater extent, due to a very large increase in electron lifetime. This can be explained by both the greater blocking capability of the D35 monolayer and the smaller degree of interaction of triiodide (iodine) with D35 compared to M14. The present work gives some insight into how the mol. structure of sensitizer affects the performance in solid-state and iodide/triiodide-based DSCs.


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