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Discerning Performance Bottlenecks of State‐of‐the‐Art Narrow Bandgap Organic Solar Cells
Atul Shukla 
,
Manasi Pranav ,
Guorui He ,
J. Terence Blaskovits ,
Davide Mascione,
Yonglin Cao,
Yufei Gong,
Drew Riley ,
Julian A. Steele ,
Eduardo Solano ,
Alexander Ehm,
Mohammad Saeed Shadabroo,
Ardalan Armin,
Safa Shoaee ,
Dietrich R. T. Zahn ,
Yongfang Li ,
Lei Meng ,
Felix Lang ,
Denis Andrienko,
Dieter Neher
,
Manasi Pranav ,
Guorui He ,
J. Terence Blaskovits ,
Davide Mascione,
Yonglin Cao,
Yufei Gong,
Drew Riley ,
Julian A. Steele ,
Eduardo Solano ,
Alexander Ehm,
Mohammad Saeed Shadabroo,
Ardalan Armin,
Safa Shoaee ,
Dietrich R. T. Zahn ,
Yongfang Li ,
Lei Meng ,
Felix Lang ,
Denis Andrienko,
Dieter Neher
Advanced Energy Materials, Start page: 2502398
Swansea University Authors:
Drew Riley , Ardalan Armin
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© 2025 The Author(s). This is an open access article under the terms of the Creative Commons Attribution License (CC BY).
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DOI (Published version): 10.1002/aenm.202502398
Abstract
Discerning loss mechanisms in organic solar cells with narrow optical bandgap is critical for the development of conventional and next‐generation photovoltaic technologies, especially for tandem and semi‐transparent solar cells. Here, all photocurrent losses are quantitatively deconvoluted in two lo...
| Published in: | Advanced Energy Materials |
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| ISSN: | 1614-6832 1614-6840 |
| Published: |
Wiley
2025
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| Online Access: |
Check full text
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| URI: | https://cronfa.swan.ac.uk/Record/cronfa69652 |
| Abstract: |
Discerning loss mechanisms in organic solar cells with narrow optical bandgap is critical for the development of conventional and next‐generation photovoltaic technologies, especially for tandem and semi‐transparent solar cells. Here, all photocurrent losses are quantitatively deconvoluted in two low‐bandgap (Eg≈1.23 eV) binary systems using structurally analogous non‐fullerene acceptors (NFAs), namely BTPV‐4F‐eC9 and BTPV‐4Cl‐eC9. Bias‐dependent free charge generation and photoluminescence studies pinpoint geminate charge transfer (CT) state recombination as the predominant photocurrent limitation in both systems, compared to parent Y6‐blends. Transient absorption spectroscopy too reveals a critical competition between CT decay and separation dynamics. Theoretical calculations uncover multiple stable molecular conformers that restrict NFA aggregation, aligning with morphological studies, resulting in poor CT separation in photoactive blends. Owing to CT loss pathways, free charge recombination in both low‐bandgap systems is closer to the Langevin limit than in PM6:Y6. Nonetheless, they exhibit overall voltage losses of ≈0.56 V comparable to PM6:Y6, and efficient exciton dissociation despite a lower driving force. Current–voltage simulations show that suppressing geminate losses can vitally balance recombination pathways to unlock photocurrent potential of low‐bandgap blends. Further optimization of the charge carrier mobility would push the PCE >16%, moving the internal quantum efficiency toward the detailed balance limit. |
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| Keywords: |
detailed balance, DFT calculations, geminate recombination, low bandgap, organic solar cells, photocurrent losses |
| College: |
Faculty of Science and Engineering |
| Funders: |
The authors acknowledge funding support from the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) through the projects Fabulous (Project Number 450968074), Extraordinaire (Project Number 460766640) and Popular (Project Number 461909888). D.A. acknowledges funding by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) for financial support through collaborative research centers (Grant Nos. TRR 146, SPP 2196, and 460766640). J.T.B and D.A. acknowledge support from the KAUST Office of Sponsored Research (OSR) under Award Nos. OSR-2018-CARF/CCF-3079 and OSR-CRG2018-3746. J.A.S. acknowledges financial support from the Australian Research Council (DE230100173). GIWAXS experiments were performed at NCD-SWEET beamline at ALBA synchrotron with the collaboration of ALBA staff. F.L. thanks the Volkswagen Foundation for funding through the Freigeist Program. D.B.R and A.A. acknowledge the financial support through the Welsh Government's Sêr Cymru II Program “Sustainable Advanced Materials” (Welsh European Funding Office – European Regional Development Fund) and by UKRI through the EPSRC Program Grant EP/T028513/1 Application Targeted and Integrated Photovoltaics and the UKRI Research England RPIF Programme (Centre for Integrative Semiconductor Materials). Open access funding enabled and organized by Projekt DEAL. |
| Start Page: |
2502398 |