Bin Liu, a postdoctoral researcher in electrical and computer engineering.
Katie Pyzyk

Device mimics plants’ photosynthesis for efficient energy transport

Humans have used solar panels to harness the sun’s energy for decades, but plants are still the best, most efficient solar energy converters. Engineers at the University of Michigan created a new device that mimics how plant leaves use photosynthesis to move the energy over long distances before using it as fuel. The method shows promise for improving solar cell efficiency. 

“Energy transport is one of the crucial steps for solar energy harvesting and conversion in solar cells,” said Bin Liu, an electrical and computer engineering researcher, in a news release. “We created a structure that can … [enable] efficient and exceptionally long-range energy transport.”

A diagram shows light hitting the semiconductor (purple) layered over the mirror-like photonic structure. The polaritons — mixtures of light, electrons and “holes” — then travel to the detector (truncated disc), where they generate current.
A diagram shows light hitting the semiconductor (purple) layered over the mirror-like photonic structure. The polaritons — mixtures of light, electrons and “holes” — then travel to the detector (truncated disc), where they generate current. Credit: Xinjing Huang and Bin Liu / Optoelectronic Components and Materials Group / University of Michigan

Conventional solar cells experience energy loss, especially at junctions between different semiconductors that create electrical currents. Plants minimize these losses by pairing light-gathering complexes with energy conversion centers. 

The engineers’ new device is a thin, light-absorbing semiconductor layered onto a structure resembling a mirror. A computer-controlled system shines light onto the semiconductor and the mirror funnels energy to a detector that converts it into electric current.

Learning from plants

Other cleantech researchers also are finding success with mimicking plants’ photosynthetic properties.

Another group at the University of Michigan developed a photosynthesis-based water-splitting device that shows promise for producing cheaper hydrogen fuel. It’s twice as efficient and stable as similar devices and grows more efficient with use.

Similarly, Purdue University researchers are developing an “artificial leaf” that collects sunlight and splits water molecules to make hydrogen.

Scientists at the University of Illinois Chicago and Argonne National Laboratory also created an artificial leaf. Theirs uses artificial photosynthesis for carbon capture. 

What’s next

The University of Michigan team says future research is needed to learn more about how the energy moves within the device.

OLED developer and manufacturer Universal Display Corporation, a developer and manufacturer of organic light emitting diode technologies, or high-resolution electronics screens, already has licensed and filed a patent application for the university researchers’ technology.