Durable, cost-effective, flexible
In her Hybrid Nano project, Academy Postdoctoral researcher Paola Vivo is developing a new type of solar cell that is cost-effective, flexible enough to be placed on clothes, and still highly efficient. Researchers are hard at work improving durability, which has proven to be a challenge for commercialisation.
Donned in cleanroom apparel, Academy Researcher Paola Vivo holds a perovskite solar cell ready for measurements. “The best thing about working as a researcher is getting to tackle exciting challenges and solve problems. There are no boring days in this job,” she says.
WHO: Paola Vivo (born 1980)
Doctor of Technology 2010, Tampere University of Technology
Master of Science 2005, Universita’ degli Studi di Napoli Federico II, Italy
- Born in Naples, Italy, lives in Lempäälä with her family.
“During the summer, I enjoy different outdoor activities in the beautiful Finnish countryside. In the winter, I prefer indoor hobbies, such as playing the piano and reading.”
Getting into the Hybrid Nano solar cell research laboratory in TUT’s cleanroom is a project in itself. When working with finicky nanotechnology, dust is a strict no-no. That means slippers and overalls, not to mention caps, breathing masks, shoe covers, and rubber gloves.
“Pull up your hood, as well,” instructs Academy Postdoctoral researcher Paola Vivo before proceeding to present her latest research.
Hybrid Nano’s current project has been going since 2013. The project’s focus is on developing novel hybrid organic-inorganic solar cells. Within Hybrid Nano, Paola Vivo decided in 2015 to focus on the hottest type of hybrid photovoltaics, perovskite solar cells (PSCs). PSCs represent one of the most exciting technologies in solar cell research in recent years. Researchers all around the globe are working with PSCs, and they are developing rapidly.
“Perovskite cells are the most significant breakthrough in solar cell technology since the 1970s. In the last few years, their power conversion efficiency has increased from just a couple per cent to over 22 per cent, close to the level of current silicon cells,” Vivo says.
Close to matching silicon in efficiency
In the cleanroom, Vivo and her collaborators create PSCs from scratch and investigate ways of improving their stability and reproducibility. Metal-halide perovskite is a material with extraordinary optoelectronic properties, such as strong photoluminescence. In addition, PSCs are efficient, light, flexible, aesthetically attractive, and much cheaper than silicon.
“However, perovskite’s big downside is its weak durability. Its lifespan often lasts for less than a year, which has made developing practical applications difficult. My dream is to create perovskite solar cells that are as stable and reproducible as traditional silicon cells,” Vivo says.
With the help of collaborators from Åbo Akademi University, Aalto University, and European key groups, Vivo has achieved great progress in the development of perovskite cells. The PSCs have had efficiency rates up to 15 per cent, and there have been marked improvements in their durability.
“Our results are first-class and compete well with those of other groups, especially considering that we only have access to relatively simple ambient-air equipment. Moisture is the biggest challenge in the manufacture of PSCs, as working in moistureless conditions would allow much better control over the crystallisation of perovskite and thus enhance the cells’ performance. I am very much looking forward to having new equipment for this purpose at TUT. However, much of our other equipment, such as the solar simulator we have here for solar research, is top-notch,” Vivo says.
There really is quite a lot of moisture in the air. Even the camera lens tends to get a bit foggy.
Dust is not the only reason for the strict protective measures in the cleanroom: PSC manufacture utilises poisonous lead. However, Vivo believes that the lead problem may soon be resolved.
“I have read publications concerning research studies where the lead has been replaced with other substances or encapsulated in such a way that it can't escape the structure. Efficiencies are still not comparable with lead-containing devices, but a lot of work is being done on this matter.”
Backpack charges batteries
In the final stages of the fabrication, the cells are stored overnight in a low-humidity cabinet.
Paola Vivo is intrigued by PSC technology’s different practical applications. She has discussed the application potential of perovskite cells with companies in varied fields of business. Once the durability issues have been overcome, there is no limit to the PSCs’ potential.
“The cells could be manufactured cost-effectively on many different surfaces. They could be put anywhere from buildings to t-shirts! For instance, I have a backpack based on hybrid cells that can charge my mobile phone when I’m walking outside in the sun,” Vivo explains.
Using PSCs for charging phone batteries might not sound like much, since there already exist other similar solutions for this. However, PSCs can benefit applications that need high efficiency, while keeping the similar advantages of other hybrid photovoltaic technologies. One example is building-integrated photovoltaics. Paola Vivo is very excited about the future possibilities third-generation solar cells may bring.
“The sun produces enough energy in one hour – free, clean, renewable energy – to last the Earth an entire year. It’s very exciting to be involved in developing technology that allows us to harness that energy more efficiently.”
Hybrid organic-inorganic nanostructures for solar cell applications (Hybrid Nano)
- Funding: Academy of Finland
- Project leader: Academy Postdoctoral researcher Paola Vivo
- Publications: 13 peer-reviewed papers in respected international journals and three Master’s theses
- What’s next: development of highly stable perovskite solar cells for smart industries and cities. Paola Vivo's new project is ASPIRE, ‘A novel integrated approach for highly reproducible and stable perovskite solar cells’, which is coordinated by Åbo Akademi University and involves researchers from Tampere University of Technology and Aalto University.