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Fluorene-Thiophene Copolymer Wire on TiO2 : Mechanism Achieving Long Charge Separated State Lifetimes

Liu, Maning LU orcid ; Makuta, Satoshi ; Tsuda, Susumu ; Russo, Salvy ; Seki, Shu ; Terao, Jun and Tachibana, Yasuhiro (2017) In Journal of Physical Chemistry C 121(46). p.25672-25681
Abstract

Insertion of interfacial molecules in bulk heterojunction and dye sensitized solar cells is effective to retard charge recombination reactions and thus to improve solar cell performance. So far, to extend charge separated state lifetime, the molecule was designed to increase distance between an n-type and a p-type semiconductors to reduce their electronic coupling. Here we investigated a series of thiophene-fluorene molecular wires on the TiO2 nanoporous surface and propose a model to explain a long-lived charge separated state. The polymer wire acts as a sensitizer aligned in parallel to the TiO2 surface and injects an electron into the TiO2 with electron injection efficiency of >80%. Time-resolved... (More)

Insertion of interfacial molecules in bulk heterojunction and dye sensitized solar cells is effective to retard charge recombination reactions and thus to improve solar cell performance. So far, to extend charge separated state lifetime, the molecule was designed to increase distance between an n-type and a p-type semiconductors to reduce their electronic coupling. Here we investigated a series of thiophene-fluorene molecular wires on the TiO2 nanoporous surface and propose a model to explain a long-lived charge separated state. The polymer wire acts as a sensitizer aligned in parallel to the TiO2 surface and injects an electron into the TiO2 with electron injection efficiency of >80%. Time-resolved microwave conductivity measurements suggest that a generated hole can be mobile, and we found with DFT calculation that a hole appears to be localized at the thiophene units which are not directly attached to the TiO2 surface. Charge recombination between the mobile electron in the TiO2 and the hole at the thiophene units is retarded to >100 ms compared to the reaction at the monomer/TiO2 interface with ∼5 ms. Monte Carlo simulation supports that this slow charge recombination occurs with the localization of the hole at the thiophene units.

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author
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publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Physical Chemistry C
volume
121
issue
46
pages
10 pages
publisher
The American Chemical Society (ACS)
external identifiers
  • scopus:85035086575
ISSN
1932-7447
DOI
10.1021/acs.jpcc.7b07295
language
English
LU publication?
no
id
4c30bca9-a1b4-4954-acf5-9492a4daaeb0
date added to LUP
2023-08-24 12:41:33
date last changed
2023-08-28 11:02:01
@article{4c30bca9-a1b4-4954-acf5-9492a4daaeb0,
  abstract     = {{<p>Insertion of interfacial molecules in bulk heterojunction and dye sensitized solar cells is effective to retard charge recombination reactions and thus to improve solar cell performance. So far, to extend charge separated state lifetime, the molecule was designed to increase distance between an n-type and a p-type semiconductors to reduce their electronic coupling. Here we investigated a series of thiophene-fluorene molecular wires on the TiO<sub>2</sub> nanoporous surface and propose a model to explain a long-lived charge separated state. The polymer wire acts as a sensitizer aligned in parallel to the TiO<sub>2</sub> surface and injects an electron into the TiO<sub>2</sub> with electron injection efficiency of &gt;80%. Time-resolved microwave conductivity measurements suggest that a generated hole can be mobile, and we found with DFT calculation that a hole appears to be localized at the thiophene units which are not directly attached to the TiO<sub>2</sub> surface. Charge recombination between the mobile electron in the TiO<sub>2</sub> and the hole at the thiophene units is retarded to &gt;100 ms compared to the reaction at the monomer/TiO<sub>2</sub> interface with ∼5 ms. Monte Carlo simulation supports that this slow charge recombination occurs with the localization of the hole at the thiophene units.</p>}},
  author       = {{Liu, Maning and Makuta, Satoshi and Tsuda, Susumu and Russo, Salvy and Seki, Shu and Terao, Jun and Tachibana, Yasuhiro}},
  issn         = {{1932-7447}},
  language     = {{eng}},
  month        = {{11}},
  number       = {{46}},
  pages        = {{25672--25681}},
  publisher    = {{The American Chemical Society (ACS)}},
  series       = {{Journal of Physical Chemistry C}},
  title        = {{Fluorene-Thiophene Copolymer Wire on TiO<sub>2</sub> : Mechanism Achieving Long Charge Separated State Lifetimes}},
  url          = {{http://dx.doi.org/10.1021/acs.jpcc.7b07295}},
  doi          = {{10.1021/acs.jpcc.7b07295}},
  volume       = {{121}},
  year         = {{2017}},
}