Self-healing solar cells could solve some major hurdles for perovskite technology, in what a multinational research team is calling a “breakthrough” for the next generation PV technology.
While perovskite solar cells are seen as the next big thing in solar, they’re also plagued by problems that researchers are still struggling with decades on – even as the world hurtles towards the day when perovskites are supposed to start supplanting silicon based solar PV.
A research team from Australia, the UK and Hong Kong say they can build perovskite cells that include a “living” damage-control service which can heal injuries caused by water and heat in the field.
“This work addresses critical issues related to defect passivation in perovskites that have hindered widespread adoption of this promising technology,” said Professor Udo Bach, study co-author and director of research for the chemical and biological engineering department at Victoria’s Monash University.
Defect passivation is a technique to fix tiny flaws in the material used in solar cells, using chemicals that attach to, or react with those faults.
“Our slow-release strategy represents a significant advancement in the field of perovskite photovoltaics. By slowly releasing the passivating agents into our perovskite material, we have been able to produce solar cells not only with enhanced performance but also extended long-term stability under real-world conditions.”
“This breakthrough could pave the way for more reliable and efficient perovskite solar cells contributing to the global transition towards sustainable energy solutions”.
Perovskite solar cells are the darling of the science world when it comes to the next big thing in solar power because they are super light and tolerate defects well.
They work by using a light-absorbing crystal structure to generate electricity from sunlight.
However, the most efficient crystals are also the least stable – degrading within days or months; they don’t work well at scale; and moisture and light cause them to degrade.
Some of the most recent research to emerge was another breakthrough from the US, where a team from Rice University found a way to stabilise the very high efficiency crystals to create a much more durable cell.
Using water and heat to heal rather than destroy
The Monash University, University of Oxford and City University of Hong Kong team used a material dubbed HUBLAs, or hindered urea/thiocarbamate bond Lewis acid-bases.
Hindered urea/thiocarbamate bonds can break and reform under the right conditions, while Lewis acid-base interactions create covalent bonds. Together, they create bonds that break and reform when in contact with heat or moisture.
The team’s paper, published in the journal Nature, said different passivation strategies have been tried in the past but humidity, heat and light create charge carrier barriers, which cause performance to deteriorate fast. Furthermore many of these are stuck in one location and can’t fix new problems when they arise once a cell is working in the field.
By using a HUBLA material, instead of water and heat causing the perovskite crystals to start deteriorating, these elements cause the material to jump into action, seeking out new sources of damage and healing them immediately.
The breakthrough resulted in perovskite solar cells with 25.1 per cent power conversion efficiency that remained stable during 1000 hours of accelerated ageing tests at 85°C and simulated solar illumination.
“We propose a “living passivator” containing dynamic covalent bonds, which can be triggered by water and heat to release additional Lewis bases, thereby healing newly generated traps. Similar to the concept of living polymerization,” the paper says.
The real-time healing strategy works during the fabrication process as well as afterwards, it said.
