Acceptor and excitation density dependence of the ultrafast polaron absorption signal in donor-acceptor organic solar cell blends

Zarrabi, Nasim, Burn, Paul L., Meredith, Paul and Shaw, Paul E. (2016) Acceptor and excitation density dependence of the ultrafast polaron absorption signal in donor-acceptor organic solar cell blends. Journal of Physical Chemistry Letters, 7 14: 2640-2646. doi:10.1021/acs.jpclett.6b00806


Author Zarrabi, Nasim
Burn, Paul L.
Meredith, Paul
Shaw, Paul E.
Title Acceptor and excitation density dependence of the ultrafast polaron absorption signal in donor-acceptor organic solar cell blends
Journal name Journal of Physical Chemistry Letters   Check publisher's open access policy
ISSN 1948-7185
Publication date 2016-07-21
Year available 2016
Sub-type Article (original research)
DOI 10.1021/acs.jpclett.6b00806
Open Access Status Not yet assessed
Volume 7
Issue 14
Start page 2640
End page 2646
Total pages 7
Place of publication Washington, DC United States
Publisher American Chemical Society
Language eng
Abstract Transient absorption spectroscopy on organic semiconductor blends for solar cells typically shows efficient charge generation within similar to 100 fs, accounting for the majority of the charge carriers. In this Letter, we show using transient absorption spectroscopy on blends containing a broad range of acceptor content (0.01-50% by weight) that the rise of the polaron signal is dependent on the acceptor concentration. For low acceptor content (<10% by weight), the polaron signal rises gradually over similar to 1 ps with most polarons generated after 200 fs, while for higher acceptor concentrations (>10%) most polarons are generated within 200 fs. The rise time in blends with low acceptor content was also found to be sensitive to the pump fluence, decreasing with increasing excitation density. These results indicate that the sub-100 fs rise of the polaron signal is a natural consequence of both the high acceptor concentrations in many donor-acceptor blends and the high excitation densities needed for transient absorption spectroscopy, which results in a short average distance between the exciton and the donor-acceptor interface.
Formatted abstract
Transient absorption spectroscopy on organic semiconductor blends for solar cells typically shows efficient charge generation within ∼100 fs, accounting for the majority of the charge carriers. In this Letter, we show using transient absorption spectroscopy on blends containing a broad range of acceptor content (0.01–50% by weight) that the rise of the polaron signal is dependent on the acceptor concentration. For low acceptor content (<10% by weight), the polaron signal rises gradually over ∼1 ps with most polarons generated after 200 fs, while for higher acceptor concentrations (>10%) most polarons are generated within 200 fs. The rise time in blends with low acceptor content was also found to be sensitive to the pump fluence, decreasing with increasing excitation density. These results indicate that the sub-100 fs rise of the polaron signal is a natural consequence of both the high acceptor concentrations in many donor–acceptor blends and the high excitation densities needed for transient absorption spectroscopy, which results in a short average distance between the exciton and the donor–acceptor interface.
Keyword Chemistry, Physical
Nanoscience & Nanotechnology
Materials Science, Multidisciplinary
Physics, Atomic, Molecular & Chemical
Chemistry
Science & Technology - Other Topics
Materials Science
Physics
Q-Index Code C1
Q-Index Status Provisional Code
Grant ID DE120101721
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Mathematics and Physics
HERDC Pre-Audit
School of Chemistry and Molecular Biosciences
 
Versions
Version Filter Type
Citation counts: TR Web of Science Citation Count  Cited 2 times in Thomson Reuters Web of Science Article | Citations
Scopus Citation Count Cited 5 times in Scopus Article | Citations
Google Scholar Search Google Scholar
Created: Sat, 03 Sep 2016, 05:00:15 EST by System User on behalf of Learning and Research Services (UQ Library)