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The Role of Energy Offsets on Charge Photogeneration Dynamics in Y-Series Molecules-Based Polymer Solar Cells

Feng, Junyi ; Wen, Guanzhao ; Hu, Rong ; Peng, Jun ; Lu, Hong ; Zhao, Ningjiu ; Zou, Xianshao LU and Zhang, Wei LU (2023) In Solar RRL 7(16).
Abstract

Recent research has revealed that low-energy offset polymer solar cells (PSCs) are capable of a power conversion efficiency of over 19%. However, it is unclear how energy offsets and the charge photogeneration process are correlated. Herein, the effect of energy offsets on charge photogeneration dynamics for Y-series molecules (Y5, Y6, Y10, and BTP-4F-12)-based PSCs with the variations of the lowest unoccupied molecular orbital energy offsets (ΔELUMO) of 0.11–0.42 eV and the highest occupied molecular orbital energy offsets (ΔEHOMO) of 0.08–0.23 eV utilizing steady-state and time-resolved spectroscopies is studied. The steady-state measurement shows that the probability of photoluminescence quenching via energy... (More)

Recent research has revealed that low-energy offset polymer solar cells (PSCs) are capable of a power conversion efficiency of over 19%. However, it is unclear how energy offsets and the charge photogeneration process are correlated. Herein, the effect of energy offsets on charge photogeneration dynamics for Y-series molecules (Y5, Y6, Y10, and BTP-4F-12)-based PSCs with the variations of the lowest unoccupied molecular orbital energy offsets (ΔELUMO) of 0.11–0.42 eV and the highest occupied molecular orbital energy offsets (ΔEHOMO) of 0.08–0.23 eV utilizing steady-state and time-resolved spectroscopies is studied. The steady-state measurement shows that the probability of photoluminescence quenching via energy transfer for the donor exciton reduces with the increasing ΔELUMO. It is found that even in PM6:Y6 with the highest ΔELUMO, ≈18% of PM6 exciton dissociated via the path of “energy transfer first and then hole transfer,” manifesting the energy transfer also plays a vital role in the process of exciton dissociation. Furthermore, it is found that the PM6 exciton can efficiently dissociate under the ΔELUMO of 0.11 eV. After photoexcitation of the Y-series molecule acceptors, the exciton dissociation efficiency enhances with the increase of ΔEHOMO. Besides, the higher energy offsets, the lower charge recombination rate in the ultrafast timescale has been found from the transient absorption measurement. These findings reveal that energy offsets are important for charge photogeneration and recombination in an ultrafast timescale for Y-series molecule-based PSCs, which may shed light on the design of high-performance PSCs.

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author
; ; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
charge photogeneration, energy offset, energy transfer, exciton dissociate, polymer solar cells
in
Solar RRL
volume
7
issue
16
article number
2300372
publisher
Wiley-VCH Verlag
external identifiers
  • scopus:85163767753
ISSN
2367-198X
DOI
10.1002/solr.202300372
language
English
LU publication?
yes
id
3cabb511-662d-4538-b6e4-2daa38dca742
date added to LUP
2023-10-16 14:40:34
date last changed
2025-04-04 15:21:30
@article{3cabb511-662d-4538-b6e4-2daa38dca742,
  abstract     = {{<p>Recent research has revealed that low-energy offset polymer solar cells (PSCs) are capable of a power conversion efficiency of over 19%. However, it is unclear how energy offsets and the charge photogeneration process are correlated. Herein, the effect of energy offsets on charge photogeneration dynamics for Y-series molecules (Y5, Y6, Y10, and BTP-4F-12)-based PSCs with the variations of the lowest unoccupied molecular orbital energy offsets (ΔE<sub>LUMO</sub>) of 0.11–0.42 eV and the highest occupied molecular orbital energy offsets (ΔE<sub>HOMO</sub>) of 0.08–0.23 eV utilizing steady-state and time-resolved spectroscopies is studied. The steady-state measurement shows that the probability of photoluminescence quenching via energy transfer for the donor exciton reduces with the increasing ΔE<sub>LUMO.</sub> It is found that even in PM6:Y6 with the highest ΔE<sub>LUMO</sub>, ≈18% of PM6 exciton dissociated via the path of “energy transfer first and then hole transfer,” manifesting the energy transfer also plays a vital role in the process of exciton dissociation. Furthermore, it is found that the PM6 exciton can efficiently dissociate under the ΔE<sub>LUMO</sub> of 0.11 eV. After photoexcitation of the Y-series molecule acceptors, the exciton dissociation efficiency enhances with the increase of ΔE<sub>HOMO</sub>. Besides, the higher energy offsets, the lower charge recombination rate in the ultrafast timescale has been found from the transient absorption measurement. These findings reveal that energy offsets are important for charge photogeneration and recombination in an ultrafast timescale for Y-series molecule-based PSCs, which may shed light on the design of high-performance PSCs.</p>}},
  author       = {{Feng, Junyi and Wen, Guanzhao and Hu, Rong and Peng, Jun and Lu, Hong and Zhao, Ningjiu and Zou, Xianshao and Zhang, Wei}},
  issn         = {{2367-198X}},
  keywords     = {{charge photogeneration; energy offset; energy transfer; exciton dissociate; polymer solar cells}},
  language     = {{eng}},
  number       = {{16}},
  publisher    = {{Wiley-VCH Verlag}},
  series       = {{Solar RRL}},
  title        = {{The Role of Energy Offsets on Charge Photogeneration Dynamics in Y-Series Molecules-Based Polymer Solar Cells}},
  url          = {{http://dx.doi.org/10.1002/solr.202300372}},
  doi          = {{10.1002/solr.202300372}},
  volume       = {{7}},
  year         = {{2023}},
}