In this work we present the synthesis, optical characterization and performance of five metal-free sensitizers for dye-sensitized solar cells (DSSC). All dyes include, for the first time, a trialkylsilyl ether group in the π-conjugated bridge (a thiophene ring). The influence of different donor unities, like triarylamine (TPA), 4H-pyranylidene and dithiafulvene has been evaluated in DSSC with a liquid I3/I− electrolyte, obtaining the best results with the 4H-pyranylidene moiety. The size and the position of the bulky group have a great importance in the efficiency of the final devices.
In order to explain the recombination processes and electron life-time, charge extraction (CE) and transient photovoltage (TPV) experiments have been carried out.
