Sub-10-fs observation of bound exciton formation in organic optoelectronic devices
File(s)
Published version
Author(s)
Type
Journal Article
Abstract
Fundamental mechanisms underlying exciton formation in organic semiconductors are complex and elusive as it occurs on ultrashort sub-100-fs timescales. Some fundamental aspects of this process, such as the evolution of exciton binding energy, have not been resolved in time experimentally. Here, we apply a combination of sub-10-fs Pump-Push-Photocurrent, Pump-Push-Photoluminescence, and Pump-Probe spectroscopies to polyfluorene devices to track the ultrafast formation of excitons. While Pump-Probe is sensitive to the total concentration of excited states, Pump-Push-Photocurrent and Pump-Push-Photoluminescence are sensitive to bound states only, providing access to exciton binding dynamics. We find that excitons created by near-absorption-edge photons are intrinsically bound states, or become such within 10 fs after excitation. Meanwhile, excitons with a modest >0.3 eV excess energy can dissociate spontaneously within 50 fs before acquiring bound character. These conclusions are supported by excited-state molecular dynamics simulations and a global kinetic model which quantitatively reproduce experimental data.
Date Issued
2022-08-23
Date Acceptance
2022-08-02
Citation
Nature Communications, 2022, 13
ISSN
2041-1723
Publisher
Nature Research
Journal / Book Title
Nature Communications
Volume
13
Copyright Statement
© The Author(s) 2022. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.
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Sponsor
Commission of the European Communities
The Leverhulme Trust
The Royal Society
Engineering & Physical Science Research Council (EPSRC)
Engineering & Physical Science Research Council (EPSRC)
Engineering & Physical Science Research Council (EPSRC)
Engineering & Physical Science Research Council (EPSRC)
Engineering & Physical Science Research Council (EPSRC)
Engineering & Physical Science Research Council (EPSRC)
Engineering & Physical Science Research Council (EPSRC)
Engineering & Physical Science Research Council (EPSRC)
Engineering & Physical Science Research Council (E
Commission of the European Communities
Engineering & Physical Science Research Council (EPSRC)
Commission of the European Communities
Engineering & Physical Science Research Council (EPSRC)
The Royal Society
Medical Research Council (MRC)
Grant Number
742708
n/a
URF\R\191026
GR/N11292
GR/S22400/01
EP/E028063/1
EP/F034601/1
EP/F021232/1
EP/I032517/1
N/A
N/A
EP/K503733/1
317232
EP/N018680/1
767112
EP/T006943/1
URF\R1\201333
MR/W011794/1
Publication Status
Published
Article Number
ARTN 4949