D-pi-A Dyes for photoactivated H2 production: the Role of Alkyl Chains in Dithienosilole Core Structures

The synthesis of H2 from sunlight and water is playing an increasingly important role in the production of clean fuels from sustainable and abundant energy sources. In this process, the role of the sensitizer, which in this work is an organic dye, is critical for optimizing the harvesting of visible light and triggering the reduction reaction at the catalytic active site. Thanks to recent advances and lower manufacturing costs, metal-free organic sensitizers have recently received an increasing importance. In the present work the efficiency of some new organic D-?-A dyes in the H2 production process is investigated. The aim of this work is to understand the possible correlation between structure and activity of such dyes, in particular the effect of introducing alkyl chains on the scaffold in order to affect several properties such as solubility, aggregation, shielding and wettability of the semiconductor. On the basis of recent studies, concerning organic molecules applied to photoactivated H2 production, it appeared that those dyes well-performing in DSSCs are in most cases suitable for H2 production. For this reason, we selected a family of organic dyes having a dithienosilole core, which are known to lead to highly efficient DSSCs, as base compounds to study the influence of structural changes.