Carbazole Dye-Sensitized Solar Cells Studied from Femtoseconds to Seconds-Effect of Additives in Cobalt- and Iodide-Based Electrolytes.

Journal:

ChemSusChem

Issue Date:

2015

Abstract(summary):

Comprehensive studies of all charge-separation processes in efficient carbazole dye-sensitized solar cells are correlated with their photovoltaic parameters. An important role of partial, fast electron recombination from the semiconductor nanoparticles to the oxidized dye is revealed; this takes place on the picosecond and sub-nanosecond timescales. The charge-transfer dynamics in cobalt tris(bipyridyl) based electrolytes and iodide-based electrolyte is observed to depend on potential-determining additives in a similar way. Upon addition of 0.5M 4-tert-butylpiridine to both types of electrolytes, the stability of the cells is greatly improved; the cell photovoltage increases by 150-200=E2=80=85mV, the electron injection rate decreases about five times (from 5 to 1=E2=80=85ps(-1) ), and fast recombination slows down about two to three times. Dye regeneration proceeds at a rate of about 1=E2=80=85mus(-1) in all electrolytes. Electron recombination from titania to cobalt electrolytes is much faster than that to iodide ones. =C2=A9 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.