HOPV12 - Blogs

4 th Hybrid and Organic Photovoltaic Conference -Uppsala 2012 202
C79 - Tailor-made synthesis of BODIPY dyes as panchromatic sensitizers
Katja Gräf, Mukundan Thelakkat
University of Bayreuth, Universitätsstr. 30, Bayreuth, 95440, DE
We present the synthesis and properties of four new BODIPY sensitizers for the application
in solid-state dye-sensitized solar cells. Meso-phenyl BODIPYs with and without TPA-donorantenna
groups (m-P-BODIPY and m-P-TPA-BODIPY) are compared to newly developed mesoethynylphenyl
BODIPYs (m-EP-BODIPY and m-EP-TPA-BODIPY).
It is known, that the phenyl group of meso-phenyl BODIPYs is oriented orthogonal relative
to the BODIPY core. This disturbs the electronic communication between both parts. From
porphyrin chemistry it is further know that an ethynyl bridge allows efficient electronic
interaction between two chromophores. Therefore, we introduced a meso-ethynylphenyl
bridge between the BODIPY core and the anchoring moiety with the goal to improve the
electron flow from the BODIPY/donor-antenna unit to the anchoring group. Additionally, we
introduced donor-antenna groups to meso-phenyl and meso-ethynylphenyl BODIPYs to reach a
panchromatic behaviour.
The meso-phenyl derivatives were synthesised starting from an aromatic aldehyde, and the
corresponding meso-ethynylphenyl BODIPYs were synthesised starting from an aliphatic
aldehyde in comparable yields. An essential part of the synthesis is the Knoevenagel-type
condensation for the covalent attachment of donor-antenna groups to the BODIPY framework.
We proved that this condensation follows an organocatalytic mechanism forming a vinylic
trans connection.
The final products were fully characterised regarding their configuration, optical and
electrochemical properties by NMR, UV-vis absorption measurements and cyclic voltammetry
experiments. The Influence of the meso-ethynyl bridge and the TPA-donor antenna group on
the properties was investigated.
Figure 1 Structures of the meso-phenyl BODIPYs (m-P-BODIPY and m-P-TPA-BODIPY) and the corresponding mesoethynylphenyl
BODIPYs (m-EP-BODIPY and m-EP-TPA-BODIPY).
By comparing the absorption of m-P-BODIPY and m-EP-BODIPY it could be proved that the
ethynyl bridge is able to improve the electronic connection between the BODIPY core and the
© SEFIN 2012