Newly invented circuit uses sunlight to self-charge

Scientists working at Penn’s Nano/Bio Interface Center have discovered the first photovoltaic circuit — a circuit that can directly convert light into electricity.

The circuit could be used in energy-saving devices and future technologies, potentially to power batteries in cell phones with energy from the sun, according to Dawn Bonnell, directior of the Nano/Bio Interface Center.

The circuit is different from others because it is made of metal and gold particles, called nanodots, that were specially designed so that certain molecules will absorb energy from the light and link to these nanodots, Bonnell explained.

This discovery was the result of collaboration between the School of Engineering and Applied Science, the Penn Chemistry Department, the University of Maryland Engineering Department and the Duke University Chemistry Department.

The scientists had conference calls with each other, and the students also communicated with each other directly, Bonnell said.

“One of the things that the Nano/Bio Interface Center tries to foster is a lot of communication because advancements are made a lot faster with collaboration,” he added.

Currently, scientists at Penn are trying to develop different kinds of devices based on these circuits, which may have the potential to harvest energy from light, Bonnell explained.

“We basically took the power-generating capabilities of an outlet, removed that and got power from a light source,” said Parag Banerjee, University of Maryland engineering graduate student.

Huge solar panels are made out of large amounts of silicon and are very expensive to mass produce, Banerjee said. The hope is that this new circuit could eliminate the need for these panels by directly using the sunlight to power itself, he explained.

As in nature, the molecules the researchers used in the circuit are similar to those used by leaves during photosynthesis, Banerjee said.

The final step of putting the molecules into the circuit had to be done in an “inert environment” in order to protect the molecules from moisture and other potentially damaging conditions, Penn Engineering post-doctoral student Sanjini Nanayakkara said.

She said the circuit will potentially lead to more energy efficiency.

Over a lifetime, the circuit could show that not as much sunlight is needed to power a certain technology or that a smaller charging time might yield more work, Nanayakkara explained.

However, the circuit needs a lot of more research and a lot more questions need to be asked, Nanayakkara said.

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