Perovskite solar cells are cheap and provide a high electricity yield per surface area, but lag behind silicon standards due to stability limitations. An international collaboration led by Prof. Dr. Antonio Abate has improved the stability of the perovskite cells by applying a new fluorinated coating to the interface between the perovskite surface and the C60 top contact layer. These advances have resulted in cells reaching an efficiency of almost 27 percent, an industry leading figure. After 1200 hours of continuous illumination, the cells showed no loss of performance. The study was conducted by teams from China, Italy, Switzerland and Germany and appears in Nature Photonics.
Prof. Abate described how the fluorinated compound slips between the perovskite and buckyball contact layers to form a nearly compact monomolecular film that chemically isolates the active layer. This barrier reduces defects and also improves the structural integrity and uniformity of the C60 layer. “It’s actually similar to the Teflon effect. The interlayer forms a chemical barrier that prevents defects while still allowing electrical contact,” Abate said.
Much of the experimental work was carried out by Guixiang Li during PhD research with Abate’s team; Li now holds a professorship at Southeast University, Nanjing. The study also involved participants from EPFL and Imperial College London.
Laboratory tests showed that perovskite solar cells equipped with the new layer achieved an efficiency of 27 percent, slightly above the 26 percent recorded without modification. The stability boost was substantial: continuous exposure to “standard sun” for 1,200 hours resulted in no loss of efficiency, while comparable devices lost 20 percent of output after just 300 hours. The coating further improved thermal stability, surviving 1,800 hours at 85 C and 200 cycles from -40 C to +85 C. The solar cells use an inverted (pin) architecture, which facilitates integration with silicon cells in tandem arrays.
Abate said the concept for the cutscene emerged during postdoctoral work in Henry Snaith’s laboratory, focusing on groundbreaking perovskite research in 2014, when the device’s efficiency was only 15 percent and declining rapidly. These new results mark progress toward highly efficient, robust optoelectronic devices using perovskite materials.
Research report:Stabilization of highly efficient perovskite solar cells via strategic interfacial contact technology
