Observing the Multiexciton State in Singlet Fission and Ensuing Ultrafast Multielectron Transfer

Multiple exciton generation (MEG) refers to the creation of two or more electron-hole pairs from the absorption of one photon. Although MEG holds great promise, it has proven challenging to implement, and questions remain about the underlying photo-physical dynamics in nanocrystalline as well as mol...

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Bibliographic Details
Published in:Science (American Association for the Advancement of Science) 2011-12, Vol.334 (6062), p.1541-1545
Main Authors: Chan, Wai-Lun, Ligges, Manuel, Jailaubekov, Askat, Kaake, Loren, Miaja-Avila, Luis, Zhu, X.-Y.
Format: Article
Language:English
Subjects:
Charge transfer
Condensed matter: electronic structure, electrical, magnetic, and optical properties
Dynamical systems
Electric fields
Electron states and collective excitations in thin films, multilayers, quantum wells, mesoscopic and nanoscale systems
Electron transfer
Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures
Electrons
Energy
Exact sciences and technology
Excitation
Excitons
Femtosecond
Fission
Fullerenes
Lasers
Materials science
Nanoparticles
Nonlinear dynamics
Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation
Optical properties of specific thin films
Pentacene
Photoelectric emission
Photons
Photovoltaic cells
Physics
Quantum efficiency
Solar energy
Thin films and multilayers
Time constants
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Summary:Multiple exciton generation (MEG) refers to the creation of two or more electron-hole pairs from the absorption of one photon. Although MEG holds great promise, it has proven challenging to implement, and questions remain about the underlying photo-physical dynamics in nanocrystalline as well as molecular media. Using the model system of pentacene/fullerene bilayers and femtosecond nonlinear spectroscopies, we directly observed the multiexciton (ME) state ensuing from singlet fission (a molecular manifestation of MEG) in pentacene. The data suggest that the state exists in coherent superposition with the singlet populated by optical excitation. We also found that multiple electron transfer from the ME state to the fullerene occurs on a subpicosecond time scale, which is one order of magnitude faster than that from the triplet exciton state.
ISSN:0036-8075
1095-9203
DOI:10.1126/science.1213986