Research highlights: Perovskites
- PDF / 747,899 Bytes
- 2 Pages / 585 x 783 pts Page_size
- 75 Downloads / 163 Views
RESEARCH HIGHLIGHTS :
Perovskites
By Prachi Patel Feature Editor: Pabitra K. Nayak
Perovskite solar cells are at the edge of commercial success. Device efficiency records break at a regular pace, while stability and optimization is progressing rapidly. The first commercial products could reach the market by 2020, just a decade since perovskite photovoltaics were first discovered. MRS Bulletin usually presents the impact of recent advances in the burgeoning field of perovskite research every quarter. This special October addendum is indicative of the breathtaking pace of perovskite research.
C
onverting the sura b faces of lead halide perovskites to water-insoluble lead oxysalt can significantly stabilize perovskite solar cells, a team led by Shuang Yang, Shangshang Chen, and Jinsong Huang of the University of North Carolina at Chapel Hill reported in a recent issue of Science (doi:10.1126/science. aax3294). Previous approaches have focused on stabiliz- (a) Schematic illustration of protection of perovskites through in situ formation of a lead sulfate top layer on the ing perovskites themselves perovskite surface. (b) Cross-sectional high-resolution transmission electron microscope image of the perovskite/ or by physically covering lead sulfate/fullerene interface (fullerene is the charge-transport layer). Credit: Science. perovskites with organic molecules. “The secondary bonding between passivation molecules oxysalt layer through a reaction of the about 97% of their initial efficiency with and the perovskite surface is typically too perovskites with sulfate or phosphate ions. simulated solar irradiation for nearly two weak to protect perovskites from attack The oxysalt capping protects the months at a realistic operation temperby moisture and oxygen,” Huang says. perovskite and suppresses defects at the ature of 65°C. “This is one of the best By contrast, the new approach involves surface. Encapsulated solar cells made reported stability so far, if not the best,” forming a compact, strongly bonded lead with the capped perovskites maintained Huang says.
A
study in the journal Materials Horizons offers an insight into the low defect density of halide perovskites. This could help materials scientists search for and design materials with similarly low defect densities for applications in optoelectronics and beyond (doi:10.1039/c9mh00606k). Defects in semiconductors, including halide perovskites, drastically impact the materials’ electronic and optical
properties. Perovskites typically have very few defects especially when solution-processed near room temperature. David Cahen of the Weizmann Institute of Science and his colleagues had previously found that defects in halide perovskites can repair themselves because of dynamic bonds that can break and reform. “This implies change toward a thermodynamically more stable state,” Cahen says.
These findings, he says, led the researchers to propose the counter-intuitive idea that “the materials’ very small free energy of formation from their binary components, which
Data Loading...
