Two triphenylamine-based metal-free organic sensitizers, D35 with a single anchor group and M14 with two anchor groups, have been applied in dye-sensitized solar cells (DSCs) with a solid hole transporting material or liquid iodide/triiodide based electrolyte. Using the molecular 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 standard AM 1.5G illumination (100 mW cm -2). Although M14 has a higher molar extinction coefficient (by ∼ 60%) and a slightly broader absorption spectrum compared to D35, the latter performs slightly better due to longer lifetime of electrons in the TiO 2, which can be attributed to differences in the molecular 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 molecular structure of sensitizer affects the performance in solid-state and iodide/triiodide-based DSCs. Organic dye sensitizers D35 and M14 have been employed in both liquid and solid state DSCs. This study shows that careful modifications in dye structure with high extinction coefficient as well as suitable surface blocking behavior will lead to more efficient sensitizers for DSCs. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.