Scientists at The University of Manchester, England (UK), have demonstrated that substituting polystyrene microgel particles for polymer could make the next generation of perovskite solar cells (PSCs) more stable longterm and significantly less expensive to produce.
In a quest to deploy the full potential of promising perovskite-based photovoltaic technologies and to make them commercially more viable, scientists have increasingly turned their attention to not only improving the longterm stability of PSCs but also reducing the relatively high cost of the hole-transport material needed in the device design. The Manchester team in fact says that the cost of producing polystyrene, which was used in the study, is one-ten-thousandth of that of producing polymers.
“Like many perovskite solar cells, our PSCs have an expensive hole transport matrix polymer as part of the device,” says Brian Saunders, professor of polymer and colloid chemistry in the School of Materials at The University of Manchester. “In our PSC, we replaced most of that polymer with low-cost polystyrene microgel particles. In another configuration we used the polystyrene microgel particles as an encapsulating layer.”
Benefits of polystyrene microgel particles
Saunders says there are two main benefits to using insulating polystyrene microgel particles in place of polymers to make perovskite solar cells: “The first is that the polystyrene microgel particles enable most of the expensive hole transport matrix polymer to be replaced by low-cost particles with only a minor (20%) decrease in power conversion efficiency. The second is that the use of the polystyrene microgel particles increased the operational stability of the PSCs — they slowed the degradation.”
Using less expensive hole transport matrix polymer without sacrificing too much efficiency
One major problem Saunders and his colleagues have aimed to address is how to use much less of the expensive hole transport matrix polymer while not sacrificing too much of the PSC’s efficiency. “We addressed this problem by replacing about 65% of the hole transport matrix polymer with polystyrene microgel particles,” the professor reports. “I cannot claim that we have solved this problem, but we have contributed a new approach towards a solution.”
Impact on future PSC designs
Saunders agrees that his research advance could have important impact on the design of future generations of solar technologies, particularly the promising concepts based on perovskite: “Because the approach should apply to other perovskite solar cells, our research offers a method with potential to decrease the cost of future PSCs by using less hole transport matrix polymer,” he projects, adding, “Polystyrene microgel synthesis is scalable — to the multi-tonne scale.”
Saunders and his team are planning to focus further research work on reducing the environmental impact of perovskite solar cells, with particular emphasis on the toxic lead. Current PSCs typically use organometallic halide perovskite, which quickly degrades when exposed to water. “Potential release of lead from PSCs is an area attracting considerable interest, and our research is focussing on designing systems that will capture lead in the event of a broken perovskite solar cell coming into contact with water.”
The study is detailed in the paper “Reducing hole transporter use and increasing perovskite solar cell stability with dual-role polystyrene microgel particles,” co-authored by Saunders and published by The Royal Society of Chemistry in Nanoscale.
Written by Sandra Henderson, Research Editor, Solar Novus Today