Researchers at the U.S. Department of Energy’s Argonne National Laboratory developed a volatile low-melting mechanism using salt additives to improve perovskite crystal growth at the atomic scale, reducing defects for high-efficiency optoelectronic devices.
Lab-grown crystals require precise, repeating atomic order to absorb light, move charge, and convert energy for technologies ranging from LEDs and solar cells to everyday camera sensors. Perovskites push those capabilities further by absorbing and emitting light with high efficiency.
Microscopic flaws scatter charge and drain energy.
Salt Additives Drive Perovskite Crystallization
Scientists at Argonne National Laboratory introduced zinc bromide and methylammonium chloride into perovskite materials. This mixture applies a eutectic method.
It lowers the melting point of the components so that parts of the film briefly liquefy during heating.
Adding salt lowers the melting point of ice, causing it to melt. Our approach behaves the same way: It creates a lower-melting environment that helps the crystal reorganize into a more stable form.
Yanqi Luo, beamline scientist in Argonne’s X-ray Science division
The added chemicals slow down crystallization and give atoms time to settle into a uniform structure as the material heats. These volatile chemicals then evaporate and disappear during heating.
They leave behind a stable perovskite film with dramatically fewer defects.
X-Ray Nanoprobes Map Atomic Motion
Researchers analyzed the salt-treated films using an X-ray beamline jointly operated by the Advanced Photon Source and the Center for Nanoscale Materials. An ultrabright X-ray nanoprobe captured snapshots at different stages of the process.
Researchers at Argonne National Laboratory developed a salt trick to address a problem with perovskite crystals.https://t.co/2Nca52MJzm
This captured how the eutectic mechanism melts, flows, and guides crystal formation.
The X-ray data revealed that zinc atoms drift toward grain boundaries where defects typically gather, smoothing out those fault lines so they no longer trap charge or waste light.
What makes this work unique is that we could map chemical composition and performance at the exact same time, in the exact same place. That type of correlated X-ray and optical microscopy is extremely rare — and it’s what allowed us to link zinc migration directly to better device behavior.
Tao Zhou, scientist at the Center for Nanoscale Materials
Scaling Up Optoelectronic Devices
Published in Science, the research demonstrates that the eutectic method produces films capable of powering LEDs with brighter output, higher efficiency, and longer lifetimes. The process yields large, uniform perovskite layers required for high-efficiency modules and manufacturable next-generation devices at scale.
The breakthrough isn’t just about making a better crystal — it’s about making a better crystal over a large area, which is the key requirement for real-world manufacturing.
Tao Zhou, scientist at the Center for Nanoscale Materials
Scientists conducted the study prior to the recent Advanced Photon Source upgrade, which transformed the facility into the brightest synchrotron X-ray source in the world.
The upgraded storage ring and the newly constructed In-Situ Nanoprobe beamline will allow researchers to move from step-by-step snapshots to continuous, real-time observation of crystal formation.