Exciton fission – one photon in, two electrons out
Emergence of the bitriplet exciton in crystalline pentacene.
Credit: © TU Berlin
”When pentacene is excited by light, the electrons in the material rapidly react,” explains Prof. Ralph Ernstorfer, a senior author of the study. “It was an open and very disputed question whether a photon excites two electrons directly or initially one electron, which subsequently shares its energy with another electron.”
To unravel this mystery the researchers used time- and angle-resolved photoemission spectroscopy, a cutting-edge technique to observe the dynamics of electrons on the femtosecond time scale, which is a billionth of a millionth of a second. This ultrafast electron movie camera enabled them to capture images of the fleeting excited electrons for the first time.
“Seeing these electrons was crucial to decipher the process,” says Alexander Neef, from the Fritz Haber Institute and the first author of the study. “An excited electron not only has a specific energy but also moves in distinct patterns, which are called orbitals. It is much easier to tell the electron apart if we can see their orbital shapes and how these change over time.”
With the images from the ultrafast electron movie at hand, the researchers decomposed the dynamics of the excited electrons for the first time based on their orbital characteristics. “We can now say with certainty that only one electron is excited directly and identified the mechanism of the excitation-doubling process,” adds Alexander Neef.
Knowing the mechanism of exciton fission is essential to using it for photovoltaic applications. A silicon solar cell enhanced with an excitation-doubling material could boost the solar-to-electricity efficiency by one-third. Such an advance could have enormous impacts since solar energy will be the dominant power source of the future. Already today large investments are flowing into the construction of these third-generation solar cells.
Journal: Nature
DOI: 10.1038/s41586-023-05814-1
Article Title: Orbital-resolved observation of singlet fission
Article Publication Date: 12-Apr-2023
Media Contact
All latest news from the category: Physics and Astronomy
This area deals with the fundamental laws and building blocks of nature and how they interact, the properties and the behavior of matter, and research into space and time and their structures.
innovations-report provides in-depth reports and articles on subjects such as astrophysics, laser technologies, nuclear, quantum, particle and solid-state physics, nanotechnologies, planetary research and findings (Mars, Venus) and developments related to the Hubble Telescope.
Newest articles
Hubble Views the Dawn of a Sun-like Star
Looking like a glittering cosmic geode, a trio of dazzling stars blaze from the hollowed-out cavity of a reflection nebula in this new image from NASA’s Hubble Space Telescope. The…
Engineering a new color palette for single-molecule imaging
A new paper published in Nature Nanotechnology outlines a way to create dozens of new “colors” to multiplex single-molecule measurements. Researchers often study biomolecules such as proteins or amino acids…
Using solar energy to generate heat at high temperatures
The production of cement, metals and many chemical commodities requires extremely high temperatures of over a thousand degrees Celsius. At present, this heat is usually obtained by combusting fossil fuels:…
