Massachusetts Institute of Technology engineers have harnessed the phenomenon known as “quantum weirdness” in order to significantly boost the light-collection system often used in solar cells, using a rather unorthodox technique in order to accomplish the feat.
“Quantum weirdness” is a term used to describe the exotic effects of quantum mechanics, such as the ability of a particle to exist in multiple places at the same time, and in a study published this week in the journal Nature Materials, the researchers explained how they used genetically-engineered viruses to provide quantum-based energy transport enhancement.
The goal of the research, mechanical engineering processor Seth Lloyd and his colleagues said, is to mimic natural photosynthesis, a process which has achieved close to 100 percent efficiency over the span of billions of years. In this process, a photon collides with a type of receptor called a chromophore, which in turn produces a quantum particle of energy called an exciton.
This exciton travels across several chromophores until it makes it to a reaction center, where its energy is harvested in order to build life-supporting molecules, Lloyd explained. The path which it travels over, however, is random and inefficient unless it utilizes quantum effects that enable it to take multiple pathways at the same time and select the best ones.
Manipulating chromophores to achieve the ‘Quantum Goldilocks Effect’
The key to efficient exciton movement relies upon the chromophores being arranged in just the right way, with the perfect amount of space separating them – a phenomenon Lloyd refers to as the “Quantum Goldilocks Effect.” Using the engineered viruses, he and his colleagues were able to manipulate artificial chromophores to alter the spacing between them.
They produced several different varieties of the virus, with each causing synthetic chromophores to have slightly different spacings, and were able to use the ones that performed best. Ultimately, they were able to more than double the speed of the excitons and increase the distance they could travel before dissipating, significantly improving the efficiency of the entire process.
The research dates back to 2008, when Lloyd saw a paper by MIT colleague Angela Belcher, an expert on engineering viruses to carry out energy-related tasks, and wondered whether or not her work could be used to help his own quest to artificially induce the quantum effect that help make natural photosynthesis so efficient.
Two weeks after the duo began collaborating, they had developed their initial test version of the engineered virus, and over the next several months, they worked on improving the receptors and the spacing. After engineering the viruses, they used laser spectroscopy and dynamical modeling to observe the light-collecting process and demonstrate that the viruses used quantum coherence in order to enhance the transport of excitons.
While the MIT team emphasizes that their results are only a proof of concept, their technique could ultimately be used to create less expensive, more efficient solar cells. While the viruses can collect and transport energy as light, they cannot yet able to produce power (for solar cells) or molecules (ala photosynthesis), but this could be achieved by adding a reaction center, Lloyd, Belcher and their colleagues added.
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