Mircea Cotlet, leader of the study and a physical chemist at Brookhaven's Center for Functional Nanomaterials (CFN), and Hsing-Lin Wang, co-author of the study and a researcher in the Chemistry Division at Los Alamos, have fabricated these new thin, transparent films in an effort to improve the use of solar panels. 

These new transparent films are semiconducting polymers "spiked" with fullerenes, which are round, cage-like molecules that consist of 60 carbon atoms. Researchers created a a flow of water droplets across a layer of polymer-fullerene solution. When the water evaporated, the materials then self-assembled into micron-sized hexagonal-shaped cells. The film ends up looking like a honeycomb, and researchers were able to develop reproducible films that spanned several square millimeters of area. 

"Though such honeycomb-patterned thin films have previously been made using conventional polymers like polystyrene, this is the first report of such a material that blends semiconductors and fullerenes to absorb light and efficiently generate charge and charge separation," said Cotlet. 

The films are transparent because the edges of the hexagons contain polymer chains that are packed together tightly while the center of these hexagons have thin and loosely packed polymer chains. The closely packed edges are capable of absorbing light and generating electricity. 

"Potentially, with future refinement of this technology, windows in a home or office could generate solar power," said Wang. 

Researchers hope to use these transparent films to create brand-new types of optical displays, energy-generating solar panels for windows and other large-scale applications. 

"Imagine a house made with windows made of this kind of material, which, combined with a solar roof, would cut its electricity costs significantly," said Cotlet. "This is pretty exciting."

This study was published in Chemistry of Materials on November 1.