Perovskite solar cells have advanced rapidly in the last decade whereby they may soon surpass traditional silicon cells as the dominant solar technology. Mesoscopic carbon-based perovskite solar cells (CPSCs) can be sequentially printed, allowing them to be produced cost effectively in bulk.
There are issues, however, around the precursor solvents used in the production process of CPSC. Dimethylformamide (DMF)−dimethyl sulfoxide (DMSO) mixtures are toxic and restricted in use in many regions, while γ-butyrolactone (GBL, analogous to GHB) is a controlled psychoactive drug with legal barriers for use in manufacturing. The Swansea team, from the university’s SPECIFIC Innovation and Knowledge Centre, discovered that a non-toxic, biodegradable solvent called γ-Valerolactone (GVL) could replace these solvents without impacting the performance of perovskite cells.
"To be truly environmentally sustainable, the way that solar cells are made must be as green as the energy they produce,” said research lead Carys Worsley, a doctorate student at Swansea University.
“As the next generation of solar technologies approaches commercial viability, research to reduce the environmental impact of large-scale production will become increasingly important."
As well as its benign legal status, GVL is also made from sustainable feedstocks. According to the SPECIFIC team, it could not only make perovskite cells more commercially viable, it could open up research into the nascent solar technology in countries that have up til now been restricted due to the hazardous nature of the existing solvents.
"Many problems need to be resolved before these technologies become a commercial reality,” said Professor Trystan Watson, research group leader. “This solvent problem was a major barrier, not only restricting large-scale manufacture but holding back research in countries where the solvents are banned.
“We hope our discovery will enable countries that have previously been unable to participate in this research to become part of the community and accelerate the development of cleaner, greener energy."
The work is published in Energy Technology.