Solar energy could be made more efficient in the future, thanks to new findings published by scientists from Stony Brook and the Department of Energy’s Brookhaven National Laboratory (BNL).
As described in a paper published on April 29 in ACS Photonics, the research assembled a nanohybrid structure that contains both biologically derived (biotic) and inorganic (abiotic) materials. This nanostructure could be used to improve the efficiency with which solar cells harvest energy from the sun.
“Today’s best solar panels can convert nearly 23 percent of the sunlight they absorb into electricity, but on average, their efficiency ranges between 15 and 18 percent,” said Mircea Cotlet, a materials scientist in BNL’s Soft and Bio Nanomaterials Group and an adjunct professor in the Materials Science and Chemical Engineering Department in the College of Engineering and Applied Sciences at Stony Brook University.
“If this efficiency can be boosted, more electricity can be generated. absorb incoming sunlight, plants and certain kinds of bacteria rely on a light-harvesting protein complex containing molecules called chromophores,” Cotlet said. “This complex funnels solar energy to the photosynthetic reaction center, where it is converted into chemical energy for metabolic processes.”
The assembled biotic-abiotic nanohybrid shows enhanced harvesting of light and generation of electrical charge carriers compared to the 2-D semiconductor-only structure. These properties increase the nanohybrid’s response to light when the structure is incorporated into a field-effect transistor (FET), a kind of optoelectronic device.”
Co-author Jia-Shiang Chen, an SBU graduate student, contributed to the research.
In designing the nanohybrid, the scientists chose atomically thin 2-D molybdenum diselenide (MoSe2) as the platform for bottom-up assembly. Molybdenum diselenide is a semiconductor, or a material whose electrical conductivity is in between that of a regular conductor (little resistance to the flow of electrical current) and insulator (high resistance). They combined MoSe2 with two strong light-harvesting nanomaterials: quantum dots (QDs) and the allophycocyanin (APC) protein from cyanobacteria.
The scientists chose the components based on their light-harvesting properties and engineered the components’ band gaps (minimum energy required to excite an electron to participate in conduction) such that a concerted stepwise energy transfer can be promoted through the nanohybrid in a directional manner. In the hybrid, energy flows from light-excited QDs to the APC protein and then to MoSe2. This energy transfer mimics natural light-harvesting systems where surface chromophores (in this case, QDs) absorb light and direct the harvested energy to intermediate chromophores (here, APC) and finally to the reaction center (here, MoSe2).
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