The cond. and solar cell performance of metal iodide-doped trialkylsulfonium iodides and polyiodides were studied as electrolytes in dye-sensitized nanocryst. solar cells (DNSCs). Nine different metal-iodide-contg. (R2R'S)I with addnl. iodine provided overall solar-to-elec. energy conversion efficiencies of over 2%, while used as electrolytes in DNSCs in simulated AM 1.5 solar light at the light intensity of 100 W m-2. The highest overall conversion efficiency, 3.1%, was achieved by using the electrolyte (Bu2MeS)I:AgI:I2 in the proportions (1:0.03:0.05). The effects from 4-tert-butylpyridine treatment of the electrodes were studied. The effects of metal-iodide doping were also studied with respect to speciation in the electrolytes and potential influence on electrochem. cond.