Nanotube solar antenna can increase the output of photovoltaic cells

The solar antenna is made of 10 micron long, 4 micron thick fiber ropes. It includes about 30 million carbon nanotubes.

Chemical engineers at the Massachusetts Institute of Technology, through the use of carbon nanotube-made solar antennas, use 100 times more solar energy than ordinary solar photovoltaic cells.

Researchers believe that this kind of antenna can capture and gather solar energy. As a result, a smaller and more powerful solar array can be created.

Michael Strano, an associate professor of chemical engineering at Charles and Hilda Roddey and head of the R&D team, explained: “Not using photovoltaic cells on the entire roof, you only need to install this tiny photovoltaic cell with an antenna in a small place. The antenna can drive photons."

Solar panels generate electricity by converting photons into electricity. The nanotube antenna can increase the number of captured photons and convert solar energy into energy through solar cells.

The solar antenna is made of 10 micron long, 4 micron thick fiber ropes. It includes about 30 million carbon nanotubes. The team created a two-layer nanotube fiber with different band gaps.

All materials carry electrons to varying degrees. When photons reach the surface of some specific materials, the electrons have a higher energy level. The reaction between electron and hole pairs forms excitons and the difference in energy level is called the band gap.

Nanotubes with smaller band gaps can be made into the inner layer of the antenna, while nanotubes with higher band gaps cover the outer layer of the antenna. Because the flow of excitons is from high energy to low energy, the outer excitons flow to the inner excitons, where they exist in a lower energy state. Therefore, when sunlight hits the surface of the material, all the photons flow to the center of the fiber.

The R&D team is now working on achieving the lowest energy loss during the photon flow to the fiber center, and each photon produces more than one exciton. At present, carbon nanotubes lose 13% of their absorbed energy, but the team's goal is to use the antenna to make energy loss only 1%.

The purpose of Mr. Strano and his team is to create a photovoltaic device that can utilize the antenna and its performance. The team will build antennas in the center of semiconductor materials so that they can be gathered before the solar cells convert the photons into electrical current.

This new antenna can also be used for devices that collect sunlight, such as night-vision goggles or telescopes.

The study of this carbon nanotube was published in the September 12 issue of Natural Materials.