Intense Lasers Cook Up Complex, Self-Assembled Nanomaterials

New technique developed at Brookhaven Lab makes self-assembly 1,000 times faster and could be used for industrial-scale solar panels and electronics

Nanoscale materials feature extraordinary, billionth-of-a-meter qualities that transform everything from energy generation to data storage. But while a nanostructured solar cell may be fantastically efficient, that precision is notoriously difficult to achieve on industrial scales. The solution may be self-assembly, or training molecules to stitch themselves together into high-performing configurations.

Now, scientists at the U.S. Department of Energy’s Brookhaven National Laboratory have developed a laser-based technique to execute nanoscale self-assembly with unprecedented ease and efficiency.

“We design materials that build themselves,” said Kevin Yager, a scientist at Brookhaven’s Center for Functional Nanomaterials (CFN). “Under the right conditions, molecules will naturally snap into a perfect configuration. The challenge is giving these nanomaterials the kick they need: the hotter they are, the faster they move around and settle into the desired formation. We used lasers to crank up the heat.”

Yager and Brookhaven Lab postdoctoral researcher Pawel Majewski built a one-of-a-kind machine that sweeps a focused laser-line across a sample to generate intense and instantaneous spikes in temperature. This new technique, called Laser Zone Annealing (LZA), drives self-assembly at rates more than 1,000 times faster than traditional industrial ovens. The results are described in the journal ACS Nano.

“We created extremely uniform self-assembled structures in less than a second,” Majewski said. “Beyond the extraordinary speed, our laser also reduced the defects and degradations present in oven-heated materials. That combination makes LZA perfect for carrying small-scale laboratory breakthroughs into industry.”

The scientists prepared the materials and built the LZA instrument at the CFN. They then analyzed samples using advanced electron microscopy at CFN and x-ray scattering at Brookhaven’s now-retiredNational Synchrotron Light Source (NSLS)—both DOE Office of Science User Facilities.

“It was enormously gratifying to see that our predictions were accurate—the enormous thermal gradients led to a correspondingly enormous acceleration!” Yager said.

Ovens versus lasers

Read more: Intense Lasers Cook Up Complex, Self-Assembled Nanomaterials

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