New D−π–A systems for dye sensitized solar cells

Resumen del póster presentado a la "5th International Conference on Hybrid and Organic Photovoltaics" celebrada en Sevilla (España) del 5 al 8 de mayo de 2013.
The conversion of solar energy in electricity is likely to play a key role as one of the technologies that can replace fossil fuels as a source of energy supply. Cheaper solar energy technologies are therefore under intensive study, and in this context dye sensitized solar cells (DSSCs) have emerged as an important class of photovoltaic devices. The dye molecular structure plays a very important role in the operation of a DSSC. Several molecular structures have been tested as sensitizers for these cells, among which stand out the donor-π-acceptor (D- π –A) systems. Such molecules have a donating group of electronic density, attached to an attractor moiety through a π-conjugated spacer. This particular arrangement allows a strong intramolecular charge transfer, thereby facilitating the electron transfer between the dye and the TiO2 electrode. In the literature, the vast majority of donors for this application include a unit of diphenyl, dialkyl or triaryl amines. In this communication we have chosen a proaromatic ring of 4Hpyranylidene and as the electron acceptor /anchoring group we have used a 2-cyanoacrylic acid moiety. Most of the organic sensitizers described in the bibliography, have a thiophene ring (or a derivative thereof) in the spacer because it provides good stability and good photovoltaic properties. To examine how the electronic character of the spacer affects the photovoltaic process, the synthesis of new molecules which incorporate into the spacer different heterocycles has been carried out. The selected bridges have been: 1-methyl-1H-pyrrole, furan, thiophene and thiazole. We have studied the thermal stability as well as the electrochemical and the optical properties of all dyes synthesized. Furthermore, measures of photovoltaic response have been carried out obtaining efficiency values between 1.44% and 5.50%.