Novel donor-acceptor heterocyclic systems bearing phthalazine, thiophene and furan groups for DSSC : synthesis and characterization

Abstract

The ever increasing consumption of fossil fuels, causing global warming and environmental pollution, has led to a greater focus on renewable energy sources and sustainable development. Among several new energy technologies, solar cells utilizing the sun as an energy source are the most promising. The commercially available solar cells are currently based on expensive inorganic silicon semiconductors. Consequently, organic solar cells, appear to be a highly promising and cost-effective option for the photovoltaic energy sector. Therefore, dye-sensitized solar cells (DSSCs) based on dye sensitizers adsorbed on nanocrystalline TiO2 electrodes have received significant attention because of their high incident solar light-to-electricity conversion efficiency, colorful and decorative natures and low cost of production. As a result, in the last two decades, a wide range of structural modifications to the donor, acceptor and pi-bridge have been carried out having in mind the preparation of organic chromophores with high performance for DSSCs. As part of an on-going research to develop efficient donor-acceptor substituted heterocyclic systems for several optoelectronic applications we synthesized phthalazines 3-4 with cyanoacetic or rhodanine anchoring groups (Figure 1). Donor-acceptor compounds 3-4 were synthesized through Suzuki coupling of bromo-phthalazine derivative 2 with commercially available (hetero)aryl-boronic acids. On the other hand, precursor 2 was prepared by reaction of phthalazinone 1 with POBr3. In this communication we report on the synthesis and characterization of novel heterocyclic dyes 3-4. The experimental results indicate that, these compounds could have potential application as sensitizers for DSSCs.