Proceedings of 6th International Conference on Hybrid and Organic Photovoltaics (HOPV14)
Publication date: 1st March 2014
The strong request for renewable energy sources has recently boosted the interest in photovoltaic devices. Among all the organic and hybrid organic-inorganic solar cells, Dye-sensitized Solar Cells (DSCs) have demonstrated one of the highest conversion efficiencies1 and a mature research and development plan. DSCs have several advantages: improved performances at low light intensities and diffuse light, color tunability, and transparency; therefore, they are very appealing for building-integrated photovoltaics (BIPV).
Metal-free organic sensitizers are accessible by simple synthetic approaches and well established purification procedures. Structurally, they can be simply modified and functionalised in order to obtain the desired spectroscopic properties between 400–700 nm.
In this work we present the synthesis and the optical and photovoltaic characterization of a series of symmetric dibranched squaraine-based sensitizers2 as a low cost and photostable alternative to the classical unsymmetrical NIR dyes. A panchromatic light harvesting was also obtained by an accurate tuning of the employed molecular moieties on the squaraine framework (Figure 1). The effect of the length of the alkyl chains as well as the effect of the functional groups on the anchoring mode and TiO2 interaction will be also discussed.
Figure 1: IPCE spectra of selected panchromatic squaraine dyes
1. Yella, A.; Lee, H.W.; Tsao, H.N.; Yi, C.; Chandiran, A.K.; Nazeeruddin, M.K.; Diau, E.W.G.; Yeh, C.Y.; Zakeeruddin, S.M.; Grätzel. M. Porphyrin-Sensitized Solar Cells with Cobalt (II/III)–Based Redox Electrolyte Exceed 12 Percent Efficiency. Science, 2011, 334, 629‒634. 2. Park, J.; Barolo, C.; Sauvage, F.; Barbero, N.; Benzi, C.; Quagliotto, P.; Coluccia, S.; Di Censo, D.; Grätzel, M.; Nazeeruddin, M.K.; Viscardi, G. Symmetric vs. asymmetric squaraines as photosensitisers in mesoscopic injection solar cells: a structure–property relationship study. Chem. Comm., 2012, 2782‒2784.