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Efficient Nanoscale Exciton Transport in Non‐Fullerene Organic Solar Cells Enables Reduced Bimolecular Recombination of Free Charges
,
Nasim Zarrabi,
Yong Kim,
Paul Meredith ,
Ardalan Armin
Advanced Materials, Volume: 35, Issue: 24
Swansea University Authors:
Drew Riley, Oskar Sandberg , Nasim Zarrabi, Yong Kim, Paul Meredith , Ardalan Armin
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DOI (Published version): 10.1002/adma.202211174
Abstract
The highest-efficiency organic photovoltaic (OPV)-based solar cells, made from blends of electron-donating and electron-accepting organic semiconductors, are often characterized by strongly reduced (non-Langevin) bimolecular recombination. Although the origins of the reduced recombination are debate...
| Published in: | Advanced Materials |
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| ISSN: | 0935-9648 1521-4095 |
| Published: |
Wiley
2023
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| Online Access: |
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| URI: | https://cronfa.swan.ac.uk/Record/cronfa63793 |
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| Abstract: |
The highest-efficiency organic photovoltaic (OPV)-based solar cells, made from blends of electron-donating and electron-accepting organic semiconductors, are often characterized by strongly reduced (non-Langevin) bimolecular recombination. Although the origins of the reduced recombination are debated, mechanisms related to the charge-transfer (CT) state and free-carrier encounter dynamics controlled by the size of donor and acceptor domains are proposed as underlying factors. Here, a novel photoluminescence-based probe is reported to accurately quantify the donor–acceptor domain size in OPV blends. Specifically, the domain size is measured in high-efficiency non-fullerene acceptor (NFA) systems and a comparative conventional fullerene system. It is found that the NFA-based blends form larger domains but that the expected reductions in bimolecular recombination attributed to the enhanced domain sizes are too small to account for the observed reduction factors. Further, it is shown that the reduction of bimolecular recombination is correlated to enhanced exciton dynamics within the NFA domains. This indicates that the processes responsible for efficient exciton transport also enable strongly non-Langevin recombination in high-efficiency NFA-based solar cells with low-energy offsets. |
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| Keywords: |
Bimolecular recombination, domain size, exciton diffusion, organic solar cells, organic photovoltaics |
| College: |
Faculty of Science and Engineering |
| Funders: |
Swansea University. This work was supported by the Welsh Government's Sêr Cymru II Program through the European Regional Development Fund, Welsh European Funding Office, and the Swansea University strategic initiative in Sustainable Advanced Materials. A.A. is a Sêr Cymru II Rising Star Fellow, and P.M. is a Sêr Cymru II National Research Chair. This work was also funded by UKRI through the EPSRC Program Grant EP/T028513/1 Application Targeted Integrated Photovoltaics. D.B.R. acknowledges the support of the Natural Sciences and Engineering Research Council of Canada (NSERC) (Grant No. PGSD3-545694-2020]). |
| Issue: |
24 |