A recent study published in the journal ACS Nano, and discussed at a press conference at the American Chemical Society National Meeting and Exhibition in Indianapolis on Monday, has discovered a new mechanism for producing energy from sunlight.
Dan Bonnell, the vice provost for research at the University of Pennsylvania and Trustee Professor of Materials Science and Engineering in the School of Engineering and Applied Science, led the study that involved a collaboration from various researchers and laboratories at the university. They hope that their findings could improve technologies for generating electricity from solar energy and create more efficient optoelectronic communications devices.
Bonell said that they are “excited to have found a process that is much more efficient than conventional photoconduction. Using such an approach could make solar energy harvesting and optoelectronic devices much better.”
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Science Daily explains the nature of the research and how it works:
“The new work centers on plasmonic nanostructures, specifically, materials fabricated from gold particles and light-sensitive molecules of porphyin, of precise sizes and arranged in specific patterns. Plasmons, or a collective oscillation of electrons, can be excited in these systems by optical radiation and induce an electrical current that can move in a pattern determined by the size and layout of the gold particles, as well as the electrical properties of the surrounding environment.”
Basically the materials can improve the scattering of light, potentially increasing the absorption of sunlight in photovoltaic solar cells.
Bonell and his colleagues first began the research that led to this study, and discovery, back in 2010 with the publishing of a paper in ACS Nano which spoke of the fabrication of plasmonic nanostructures, which could induce and conduct an electrical current across molecules.
Bonell stated that “we hypothesized that, when plasmons are excited to a high energy state, we should be able to harvest the electrons out of the material. If we could do that, we could use them for molecular electronics device applications, such as circuit components or solar energy extraction.”
In order to examine the plasmonic nanostructures further and better determine its uses, the researchers varied the different components of the mechanism, both the size of the gold nanoparticles, the size of the prophyin molecules, and the spacing between the different particles.
Bonell explained that “in our measurements, compared to conventional photoexcitation, we saw increases of three to 10 times in the efficiency of our process. And we didn’t even optimize the system. In principle you can envision huge increases in efficiency.”
By improving the efficiency of light absorption and energy produced, they could greatly increase the power produced from small solar cells. Bonell suggested that “you could imagine having a paint on your laptop that acted like a solar cell to power it using only sunlight.”