Now, a team of researchers at the University of Washington and the National Renewable Energy Laboratory (NREL) has developed a new technique for tracking how halogen atoms (such as iodine and chlorine) compete to grow perovskite crystals. This information could help researchers design new strategies for synthesizing high-quality perovskite materials.
The team's technique, time-resolved X-ray photoemission spectroscopy (TR-XPS), uses an X-ray beam to excite electrons in a perovskite sample. The energy of these electrons can then be measured to identify the different elements present in the sample. By following how these elements change over time, the team could track how the perovskite crystal grows.
In their experiments, they found that iodine and chlorine compete to grow perovskite crystals in different ways. Chlorine reacts more quickly with lead to form perovskite, but iodine eventually takes over and forms a more stable perovskite crystal. This suggests that a two-step synthesis process could be used to grow high-quality perovskite crystals, with chlorine used in the first step to quickly form a perovskite nucleus and iodine used in the second step to stabilize the crystal structure.
The team's findings could help to improve the synthesis of perovskite materials for a variety of applications. Perovskite solar cells, for example, could benefit from the use of high-quality perovskite crystals that are more efficient at converting sunlight into electricity. Perovskite light-emitting diodes (LEDs) could also benefit from the use of high-quality perovskite crystals that emit light more efficiently.
Overall, this work provides a new tool for studying the growth of perovskite crystals and could lead to the development of new strategies for synthesizing high-quality perovskite materials for a variety of applications.
