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Silver, copper, zinc used to make plastic conductive, more transparent

Jay Guo, senior author of the study, holds a sheet of flexible transparent conductor. (Image courtesy of Robert Coelius/University of Michigan Engineering, Communications & Marketing).

Researchers at the University of Michigan have made plastic conductive while also making it more transparent by incorporating silver, copper, zinc and aluminium to sheets of the material.

In a paper published in the journal Nature Communications, the scientists explain that their creation is aimed at improving window-mounted infrared solar cells, large touchscreens, and LED light panels.

The new material is aimed at improving window-mounted infrared solar cells, large touchscreens, and LED light panels

In detail, the experts created a three-layer anti-reflection surface where a conductive metal layer is sandwiched between two “dielectric” materials that allow light to pass through easily. The dielectrics reduce the reflection from both the plastic and metal layer between them.

The dielectrics chosen in this case were aluminium oxide and zinc oxide. On the side closest to the light source, the aluminum oxide reflects less light back to the source than the plastic surface would. Then comes the metal layer, composed of silver with an addition of 6.5 nanometers of copper, and then zinc oxide helps guide the light into the plastic surface. 

“Some light still gets reflected back where the plastic meets the air on the opposite side, but overall, the light transmission is better than the plastic alone,” the authors of the study said in a media statement. “The transmittance is 88.4%, up from 88.1% for the plastic alone.”

The article provides a step-by-step guide on how to produce this new material. Thus, the expectation is that other researchers get inspired to design similar sandwich-style flexible, highly transparent conductors, which allow even more light through than the plastic alone.

“The tricks are selecting the right dielectrics and then figuring out the right thickness for each to suppress the reflection of the thin metal,” researchers said. “In general, the material between the plastic and metal should have a higher refractive index, while the material nearest the display or light source should have a lower refractive index.”