Schematic of the novel perovskite material with organic molecules that can enhance its electronic properties. Image: Jingjing Xue and Rui Wang/UCLA Samueli School of Engineering.Materials scientists at the University of California, Los Angeles (UCLA) and their colleagues have discovered that perovskites, a class of promising materials for producing low-cost, high-performance solar cells and LEDs, have a previously unutilized molecular component that can be used to tune their electronic property.
Named after Russian mineralogist Lev Perovski, perovskite materials have a crystal-lattice structure of inorganic molecules like that of ceramics, but with organic molecules interlaced throughout. Up to now, these organic molecules only appeared to serve a structural function and could not directly affect the perovskites' electronic performance.
Led by UCLA researchers, the new study shows that when the organic molecules are designed properly, they not only maintain the crystal lattice structure, but can also contribute to the materials' electronic properties. This discovery opens up new possibilities for improving the design of perovskite materials, potentially leading to better solar cells and LEDs. The researchers report their findings in a paper in Science.
"This is like finding an old dog that can play new tricks," said Yang Yang, professor of engineering at the UCLA Samueli School of Engineering and the principal investigator on the research. "In materials science, we look all the way down to the atomic structure of a material for efficient performance. Our postdocs and graduate students didn't take anything for granted and dug deeper to find a new pathway."
In order to make a better-performing perovskite material, the researchers incorporated a specially designed organic molecule – a pyrene-containing organic ammonium. On its exterior, the positively charged ammonium molecule connects to the pyrene molecules, which comprise a quadruple ring of carbon atoms. This molecular design provided additional electronic tunability of the perovskites.
"The unique property of perovskites is that they have the advantage of high-performance inorganic semiconductors, as well as easy and low-cost processability of polymers," said study co-lead author Rui Wang, a UCLA postdoctoral scholar in materials science and engineering. "This newly enhanced perovskite material now offers opportunities for improved design concepts with better efficiency."
To demonstrate the new perovskite's added effectiveness, the team built a photovoltaic (PV) cell prototype with the material, and then tested it under continuous light for 2000 hours. The new cell continued to convert light to energy at 85% of its original efficiency at the end of this testing period. This contrasts with a PV cell made of the same materials but without the added altered organic molecule, which retained only 60% of its original efficiency.
This story is adapted from material from UCLA, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.