Multi-functional Chromophores

Licentiate thesis, 2016

As the push towards green energy become stronger, more efficient systems needs to be developed to compete with fossil fuel based systems. In modern Grätzel solar cells, most of the energy losses are inherited from the choice of chromophore and metal oxide surface. Within this work we will present synthetic strategies for two chromophore that not only are able to absorb light but potentially also able to increase solar cell efficiencies by a secondary function. The first synthetic target is a functionalized 1,3-diphenylisobenzofuran chromophore that is capable to self-assemble in a slip-stack manner to form a multi-chromophore system that supports singlet fission. The chromophore core is constructed via a Gringard reaction while the coupling between the linker and the chromophore moiety is performed by a sp2-sp3 Suzuki-Miyaura type coupling of a bromo-aryl with a terminal alkene via a hydroboration step. The synthesis is designed to be flexible to allow for incorporations of a variety of linkers and anchor groups, as well as being mild enough to ensure stability of the otherwise sensitive 1,3-diphenylisobenzofuran functionality. The second synthetic target is a metal complex that consist of a ruthenium (II) cation and three bidentate ligands, two of which are 2,2’-bipyridine-4,4’-bis(ethoxycarbonyl) and one 2-(propane-2-sulfinylmethyl)-pyridine. The sulfoxide complex can be switched between two forms by photoisomerization. Each isomer increase stability of different oxidation state upon the metal cation, thereby decrease potential losses as the charge separated state is less prone to quenching quick recombination.