Organic molecules improve the electronic properties of 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. This newly enhanced perovskite material now offers opportunities for improved design concepts with better efficiency.Rui Wang
A collaborative study has developed a new approach to powering up nanomaterials in a development that could help a range of applications in electronics. It was demonstrated how perovskites, a class of compounds that offer a range of engineered materials due to different cations that can be embedded in their structure, have a previously unutilized molecular component that can further tune their electronic property. The breakthrough could lead to better design of the next generation of inexpensive but high-performance solar cells and LEDs.
Perovskite materials have a crystal-lattice structure of inorganic molecules similar to that of ceramics, as well as organic molecules that are interlaced throughout. To date, such organic molecules seemed to only act as a structural function and do not directly contribute to perovskites' electronic performance. However, as detailed in Science [Xue et al. Science (2021) DOI: 10.1126/science.abd4860], the researchers have shown that when the organic molecules are designed in a certain way, they not only can help maintain the crystal lattice structure, but also contribute to the materials' electronic properties.
To produce their improved perovskite material, the researchers introduced a specially designed organic molecule, a pyrene-containing organic ammonium. On the outside, the positively charged ammonium molecule was connected to pyrene molecules, which offered additional electronic tunability of the perovskites. As co-lead author Rui Wang said, “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. This newly enhanced perovskite material now offers opportunities for improved design concepts with better efficiency.”
In order to test the improved performance of the perovskites, the team produced a prototype of a photovoltaic cell using the materials, before demonstrating it in conditions of continuous light for 2,000 hours. This showed the new cell was able to continue to convert light into energy at 85% of its original efficiency. If this is compared with a photovoltaic cell made of the same materials but which did not have the altered organic molecule added, this only managed to retain 60% of its original efficiency.
The study was by a team from UCLA, in collaboration with the US Department of Energy's National Renewable Energy Laboratory (NREL), as well as the University of Toledo, Yangzhou University and Soochow University in China, Monash University in Australia, and the Lawrence Berkeley National Laboratory, in work funded by the US Department of Energy.