Imagine a world where solar energy is not just efficient but also incredibly durable, even in scorching heat. That’s exactly what a team of researchers led by Professor Dong Suk Kim at the UNIST Graduate School of Carbon Neutrality and Professor Tae Kyung Lee at Gyeongsang National University is working towards. They’ve come up with an innovative way to boost the heat resistance of perovskite solar cells, which could be a game-changer in solar technology.
These new solar cells start with an impressive efficiency of 25.56% and, more importantly, they hold onto over 85% of that efficiency after being subjected to 85°C and 85% relative humidity for a whopping 1,000 hours. This is a significant breakthrough, especially when you consider the challenges perovskite cells have faced with heat stability. The findings, published in Energy & Environmental Science, highlight the potential for these cells to be commercially viable.
Perovskite solar cells are often seen as the future of solar technology because they promise to be more efficient and cost-effective than traditional silicon cells. However, their sensitivity to heat has been a major roadblock. Unlike silicon cells, which can handle high encapsulation temperatures, perovskite cells have struggled when temperatures climb above 110°C.
The researchers tackled this issue by swapping out the commonly used additive 4-tert-butylpyridine (tBP) with ethylene carbonate (EC). This change bumped the glass transition temperature of the hole transport layer up to 125°C from below 80°C, making the cells much more stable in hot environments.
These reengineered cells achieved a power conversion efficiency (PCE) of 25.56%, which is the highest among tBP-free cells. They also maintained this efficiency even after being encapsulated. Under rigorous international testing conditions of 85°C and 85% humidity, the cells retained an efficiency of 21.7% after 1,000 hours. Plus, when scaled up to a module of 100 cm², they still held a high efficiency of 22.14%.
This success is largely due to ethylene carbonate’s ability to evenly dissolve lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), which enhances charge transport in the hole transport layer. Professor Kim noted, “Through this research, we’ve developed a hole transport layer system that retains high efficiency while ensuring stability in high-temperature and high-humidity environments,” underscoring the significant progress towards practical applications.
