New insights into how a certain class of photovoltaic materials can effectively convert sunlight into electricity can help the development of these materials so that they can replace traditional silicon solar cells. A study conducted by researchers at Pennsylvania State University revealed the unique properties of cheap and fast-producing halide perovskites, and this information will guide the development of next-generation solar cells. The study was published in the journal Chem.
John Asbury, an associate professor of chemistry at Penn State University and an important author of the paper, said: "Silicon solar cells are often found on rooftops or roadsides today, but researchers have been actively searching for new photovoltaic materials that are easier to process into solar cells. This is because the processing of silicon solar cells is very complicated and it is difficult to expand to the scale level required for 10% of our total electricity demand. "
Because of these complications, researchers have been looking for cheaper materials to replace silicon solar cells for faster processing. They are particularly interested in materials that can be processed using a "roll-to-roll" manufacturing technique. Similar to the way newspapers are printed, this technology allows low-cost, high-volume production. These materials must be processed from solution, just like the ink printed on a page.
Asbury said: "After 40 years of intensive research on this type of material, researchers have found no material other than a material called" halide perovskite "that can approach the properties of silicon." Calcium halide Titanium ore appears to have unique tolerances to defects in its structure that enable them to efficiently convert solar energy into electricity, while other materials with similar defects do not.
Prior to this study, however, it was unclear what made halogen perovskite's tolerance for defects so high. Researchers used ultrafast infrared imaging to study how the structure and composition of these materials affect their ability to convert sunlight into electricity.
They determined that halide perovskites have the unique ability to maintain crystal structures, even if the atoms in their crystals undergo unusually large-scale vibrational motion. All materials experience the vibrational motion of their atoms, which usually needs to be suppressed by having a very hard crystal structure, such as silicon, to hold the atoms firmly in place. However, according to current research, halide perovskites are very soft, which allows their atoms to move around and helps improve efficiency.
"Interestingly, this large-scale atomic motion often results in the loss of crystal structure in other materials, resulting in defects that consume energy in the excited state," Asbury explained. "But for halogenated perovskites, researchers can use chemical methods to replace the charged atoms in the material to adjust the amplitude of this atomic-scale motion. This will allow us to improve the performance and stability of halogenated perovskite materials."
"At present, halide perovskites usually contain toxic elements such as lead, and they have not reached the level of stability required to replace silicon solar cells. The insights from this research will allow us to formulate rules to use roll-to-roll manufacturing processes to design new Halide perovskite. This will guide the development of the next generation of perovskite materials, which are more stable and contain less toxic elements, such as tin instead of lead. "