Organic sensitizers bearing a trialkylsilyl ether group for liquid dye sensitized solar cells

• Synthesis and characterization of organic sensitizers with a trialkylsilyloxy group on the π-spacer.
• DSSC efficiency was highly dependent on the size and position of the silyloxy group.
• Best efficiencies were obtained with the 4H-pyranylidene, followed by TPA and dithiafulvene systems.

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.

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