DSSC-photoactive
Our activity in dye-sensitized solar cells (DSSCs) started around 2011 as a natural continuation of our previous work on D–π–A molecular systems for nonlinear optics. Building on this expertise, we moved into the design of organic dyes for photovoltaic applications, with a strong focus on understanding how molecular structure translates into device performance.
Over the years, we have developed a wide range of organic sensitizers based on push–pull architectures, particularly incorporating 4H-pyranylidene and arylamine donor units combined with tailored π-conjugated spacers and anchoring groups. In total, around 200 new dyes have been synthesized and characterized within the group, providing a broad platform to establish structure–property relationships. Special attention has been devoted to controlling intramolecular charge transfer, energy level alignment and light absorption properties through rational molecular design.
A key aspect of our work has been the control of dye aggregation at the semiconductor surface. This has been addressed through structural modification, including the introduction of bulky substituents such as silyl ether groups, which reduce intermolecular interactions and improve device performance. In some cases, this strategy has enabled high open-circuit voltages (Voc) without the need for additional anti-aggregation additives.
In parallel, we have developed an original approach based on calix[4]arene scaffolds as platforms to organize multiple chromophores within a single molecule. These multichromophoric systems allow the incorporation of several D–π–A units, increasing the molar extinction coefficient and broadening the absorption range, while maintaining controlled spatial separation between chromophores . This strategy not only enhances light-harvesting efficiency but also helps to reduce aggregation and improve dye organization at the TiO₂ surface. More recently, this concept has been extended through the modification of the π-spacer, enabling further tuning of optical and electrochemical properties and improving device performance.
One of the main strengths of our research is its fully integrated approach. In addition to molecular design and synthesis, we fabricate and test the corresponding devices. Over the years, we have established a dedicated laboratory for the preparation and optimization of DSSCs, allowing full control over the process, from molecular design and characterization to device assembly and evaluation. This direct feedback between chemistry and device performance is central to our methodology. Our work has been carried out in collaboration with national and international research groups and has led to competitive device efficiencies, currently exceeding 9% in collaborative studies.
In parallel, we have explored strategies to improve device efficiency beyond the dye itself, including the modification of TiO₂ photoanodes and the development of hybrid interfaces. These studies have contributed to a deeper understanding of charge transport, recombination processes and interfacial phenomena.
More recently, our research has expanded towards related photovoltaic technologies. In particular, new families of hole-transport materials (HTMs) have been developed for perovskite solar cells, extending our expertise in π-conjugated systems and charge-transfer materials to emerging high-efficiency devices.
Today, DSSCs are gaining renewed interest in low-light conditions, such as indoor environments under LED or fluorescent illumination, making them especially attractive for applications in building-integrated photovoltaics (BIPV) and smart energy systems.
Selected publications
Researchers involved in this line:
Santiago Franco, Belén Villacampa, María Jesús Blesa
Ideas for figures / images (to include later)
- Scheme of a DSSC device (general structure and working principle)
- Examples of D–π–A molecular structures developed in the group
- Photographs of the laboratory and/or DSSC device fabrication setup
- Representative J–V curves and/or IPCE spectra of selected devices