Researchers at The University of Texas at Austin and the University of California, Riverside have recently discovered a way to transfer the energy between silicon and organic, carbon-based molecules. The breakthrough of silicon light energy transfer can be used with a wide variety of information storage in quantum computing, medical imaging, and solar energy conversion.
Silicon is a very important component for making electronics and is used in everything from solar panels to our computers and cell phones. Luckily, silicon is also one of the most abundant materials on Earth. Silicon converts photons into electricity and is especially good at converting red photons. However, when converting with blue photons, the silicon loses most of its energy as heat. The blue photons can carry twice as much energy as red photons, so the team has been working on a way to effectively use that energy.
They may have exceeded their own expectations for silicon light energy transfer. The scientists were able to create a hybrid material that boosts the silicon’s efficiency by pairing it with a carbon-based material. Not only did they discover this can convert the blue photons into pairs of red photons, but it also gives it the ability to work in reverse and convert red light into blue light. This is key for future medical treatments and quantum computing.
Sean Roberts, Assistant Professor of Chemistry at UT Austin explains:
The organic molecule we’ve paired silicon with is a type of carbon ash called anthracene. It’s soot, The paper describes a method for chemically connecting silicon to anthracene, creating a molecular power line that allows energy to transfer between the silicon and ash-like substance. We now can finely tune this material to react to different wavelengths of light. Imagine, for quantum computing, being able to tweak and optimize a material to turn one blue photon into two red photons or two red photons into one blue. It’s perfect for information storage.
Scientists have been thinking for many years that if they could effectively pair silicon with an organic material that it would significantly improve the ability to turn light into electricity. Roberts and his team created what is called, “spin-triplet exciton transfer,” which is a particular type of energy transfer from the carbon-based material to silicon. They used tiny chemical wires that connect silicon nanocrystals to anthracene, thus producing the energy transfer.
The challenge has been getting pairs of excited electrons out of these organic materials and into silicon. It can’t be done just by depositing one on top of the other,” Roberts said. “It takes building a new type of chemical interface between the silicon and this material to allow them to electronically communicate.
Working on the project with Roberts was Emily Raulerson, a graduate student, together they measured the effect in a specially designed molecule that attaches to a silicon nanocrystal, the innovation of collaborators Ming Lee Tang, Lorenzo Mangolini and Pan Xia of UC Riverside. Using an ultrafast laser, Roberts and Raulerson found that the new molecular wire between the two materials was not only fast, resilient and efficient, but it could also effectively transfer about 90% of the energy from the nanocrystal to the molecule.
“We can use this chemistry to create materials that absorb and emit any color of light,” said Raulerson, who says that, with further finetuning, similar silicon nanocrystals tethered to a molecule could generate a variety of applications, from battery-less night-vision goggles to new miniature electronics.
Working in conjunction with UC Riverside, Tang’s lab pioneered how to attach the organic molecules to the silicon nanoparticles, and Mangolini’s group engineered the silicon nanocrystals.
The novelty is really how to get the two parts of this structure—the organic molecules and the quantum confined silicon nanocrystals—to work together,” said Mangolini, an associate professor of mechanical engineering. “We are the first group to put the two together.
