M. Jansson, F. Ishikawa, W. M. Chen, I. A. Buyanova,
Published open access in ACS Nano.
In photonics and optoelectronics, controlling the energy – or wavelength – of the light is often vitally important. For example, when light from the sun impinges on a solar cell, only the light with enough energy can actually be absorbed by it, contributing to the output power, while light with too low energy is transmitted, and therefore lost.
In the research paper (linked above) by Mattias Jansson and collaborators, they demonstrate how a semiconductor nanowire (a wire which is a thousand times thinner than a human hair) can efficiently absorb low energy light and convert it to light of a higher energy, a process which is called energy upconversion. Such an upconversion process, if efficient enough, could in the future be implemented on existing solar cell technology, or even form the basis of a completely new type of high-efficiency solar cell, to harvest also the low energy part of the solar spectrum. In the paper, they also show that by properly selecting the nanowire material, they could measure an upconversion efficiency significantly larger than what has previously been measured in semiconductor upconversion devices.