Modulating Exciton Delocalization in Organic Solar Cells Through Tailored Local Structures and Dipole Offset of Acceptor

Baobing Fan; Lingchen Kong; Qian Li; Urvashi Bothra; Wei Gao; Sen Zhang; Francis R. Lin; Dangyuan Lei; Wei Ma; Chun Sing Lee; David S. Ginger; Alex K.-Y. Jen

doi:10.1002/adfm.202515391

Modulating Exciton Delocalization in Organic Solar Cells Through Tailored Local Structures and Dipole Offset of Acceptor

Baobing Fan (Co-first Author)
, Lingchen Kong (Co-first Author)
, Qian Li (Co-first Author)
, Urvashi Bothra
, Wei Gao
, Sen Zhang
, Francis R. Lin
, Dangyuan Lei
, Wei Ma
, Chun Sing Lee
, David S. Ginger
, Alex K.-Y. Jen^*

^*Corresponding author for this work

Research output: Journal Publications and Reviews › RGC 21 - Publication in refereed journal › peer-review

8 Citations (Scopus)

Abstract

The charge-transfer states are strongly associated with the charge recombination in organic solar cells (OSCs), leading to severe energy losses in relevant devices. Enhancing exciton delocalization could mitigate these losses by facilitating dissociation of excitons into free charge carriers. However, the correlation between exciton delocalization and single-molecule properties is currently unclear, and the influence of exciton delocalization on non-geminate recombination and associated triplet formation is rarely studied. Herein, we demonstrate that a larger offset between the ground- and excited-state dipole moments will facilitate the exciton delocalization of non-fullerene acceptors (NFAs). In addition, the hole transfer efficiency is not solely affected by the population of delocalized excitons. Among the three NFAs studied, only the perfluorinated one, FTh-4F, with moderate exciton delocalization, shows simultaneously suppressed triplet formation and prolonged carrier lifetime, resulting in an impressive power conversion efficiency (PCE) of 20.2% in the derived OSC device. We also highlight the feasibility of applying tailored halogenation on NFAs to modulate exciton delocalization for mitigating non-geminate recombination and triplet formation in OSCs. © 2025 Wiley-VCH GmbH.

Original language	English
Article number	e15391
Number of pages	8
Journal	Advanced Functional Materials
Volume	36
Issue number	32
Online published	26 Dec 2025
DOIs	https://doi.org/10.1002/adfm.202515391
Publication status	Published - 20 Apr 2026

Funding

Baobing Fan, Lingchen Kong, and Qian Li contributed equally to this work. A.K.Y.J. thanks the sponsorship of the Lee Shau-Kee Chair Professor (Materials Science) and the support from the APRC Grants (9380086, 9610419, 9610440, 9610492, 9610508) of the City University of Hong Kong, the MHKJFS Grant (MHP/054/23) and MRP Grant (MRP/040/21X) from the Innovation and Technology Commission of Hong Kong, the Green Tech Fund (202020164) from the Environment and Ecology Bureau of Hong Kong, the GRF grants (11304424, 11307621, 11316422) and CRS grants (CRS_CityU104/23, CRS_HKUST203/23) from the Research Grants Council of Hong Kong, and the Guangzhou Huangpu Technology Bureau (2022GH02). D.Y.L. thanks the financial support from the Research Grants Council of Hong Kong through a Collaborative Research Equipment Grant (C1015-21EF).

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

SDG 7 Affordable and Clean Energy

Research Keywords

dipole moment
exciton delocalization
halogenation
non-fullerene acceptor
organic solar cells

RGC Funding Information

RGC-funded

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10.1002/adfm.202515391

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Cite this

@article{935997f46b6f41ad8ad66ad8b3c52973,

title = "Modulating Exciton Delocalization in Organic Solar Cells Through Tailored Local Structures and Dipole Offset of Acceptor",

abstract = "The charge-transfer states are strongly associated with the charge recombination in organic solar cells (OSCs), leading to severe energy losses in relevant devices. Enhancing exciton delocalization could mitigate these losses by facilitating dissociation of excitons into free charge carriers. However, the correlation between exciton delocalization and single-molecule properties is currently unclear, and the influence of exciton delocalization on non-geminate recombination and associated triplet formation is rarely studied. Herein, we demonstrate that a larger offset between the ground- and excited-state dipole moments will facilitate the exciton delocalization of non-fullerene acceptors (NFAs). In addition, the hole transfer efficiency is not solely affected by the population of delocalized excitons. Among the three NFAs studied, only the perfluorinated one, FTh-4F, with moderate exciton delocalization, shows simultaneously suppressed triplet formation and prolonged carrier lifetime, resulting in an impressive power conversion efficiency (PCE) of 20.2\% in the derived OSC device. We also highlight the feasibility of applying tailored halogenation on NFAs to modulate exciton delocalization for mitigating non-geminate recombination and triplet formation in OSCs. {\textcopyright} 2025 Wiley-VCH GmbH.",

keywords = "dipole moment, exciton delocalization, halogenation, non-fullerene acceptor, organic solar cells",

author = "Baobing Fan and Lingchen Kong and Qian Li and Urvashi Bothra and Wei Gao and Sen Zhang and Lin, \{Francis R.\} and Dangyuan Lei and Wei Ma and Lee, \{Chun Sing\} and Ginger, \{David S.\} and Jen, \{Alex K.-Y.\}",

year = "2026",

month = apr,

day = "20",

doi = "10.1002/adfm.202515391",

language = "English",

volume = "36",

journal = "Advanced Functional Materials",

issn = "1616-301X",

publisher = "Wiley-VCH Verlag GmbH",

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Modulating Exciton Delocalization in Organic Solar Cells Through Tailored Local Structures and Dipole Offset of Acceptor. / Fan, Baobing (Co-first Author); Kong, Lingchen (Co-first Author); Li, Qian (Co-first Author) et al.
In: Advanced Functional Materials, Vol. 36, No. 32, e15391, 20.04.2026.

Research output: Journal Publications and Reviews › RGC 21 - Publication in refereed journal › peer-review

TY - JOUR

T1 - Modulating Exciton Delocalization in Organic Solar Cells Through Tailored Local Structures and Dipole Offset of Acceptor

AU - Fan, Baobing

AU - Kong, Lingchen

AU - Li, Qian

AU - Bothra, Urvashi

AU - Gao, Wei

AU - Zhang, Sen

AU - Lin, Francis R.

AU - Lei, Dangyuan

AU - Ma, Wei

AU - Lee, Chun Sing

AU - Ginger, David S.

AU - Jen, Alex K.-Y.

PY - 2026/4/20

Y1 - 2026/4/20

N2 - The charge-transfer states are strongly associated with the charge recombination in organic solar cells (OSCs), leading to severe energy losses in relevant devices. Enhancing exciton delocalization could mitigate these losses by facilitating dissociation of excitons into free charge carriers. However, the correlation between exciton delocalization and single-molecule properties is currently unclear, and the influence of exciton delocalization on non-geminate recombination and associated triplet formation is rarely studied. Herein, we demonstrate that a larger offset between the ground- and excited-state dipole moments will facilitate the exciton delocalization of non-fullerene acceptors (NFAs). In addition, the hole transfer efficiency is not solely affected by the population of delocalized excitons. Among the three NFAs studied, only the perfluorinated one, FTh-4F, with moderate exciton delocalization, shows simultaneously suppressed triplet formation and prolonged carrier lifetime, resulting in an impressive power conversion efficiency (PCE) of 20.2% in the derived OSC device. We also highlight the feasibility of applying tailored halogenation on NFAs to modulate exciton delocalization for mitigating non-geminate recombination and triplet formation in OSCs. © 2025 Wiley-VCH GmbH.

AB - The charge-transfer states are strongly associated with the charge recombination in organic solar cells (OSCs), leading to severe energy losses in relevant devices. Enhancing exciton delocalization could mitigate these losses by facilitating dissociation of excitons into free charge carriers. However, the correlation between exciton delocalization and single-molecule properties is currently unclear, and the influence of exciton delocalization on non-geminate recombination and associated triplet formation is rarely studied. Herein, we demonstrate that a larger offset between the ground- and excited-state dipole moments will facilitate the exciton delocalization of non-fullerene acceptors (NFAs). In addition, the hole transfer efficiency is not solely affected by the population of delocalized excitons. Among the three NFAs studied, only the perfluorinated one, FTh-4F, with moderate exciton delocalization, shows simultaneously suppressed triplet formation and prolonged carrier lifetime, resulting in an impressive power conversion efficiency (PCE) of 20.2% in the derived OSC device. We also highlight the feasibility of applying tailored halogenation on NFAs to modulate exciton delocalization for mitigating non-geminate recombination and triplet formation in OSCs. © 2025 Wiley-VCH GmbH.

KW - dipole moment

KW - exciton delocalization

KW - halogenation

KW - non-fullerene acceptor

KW - organic solar cells

UR - https://www.scopus.com/pages/publications/105026006582

UR - https://www.scopus.com/pages/publications/105026006582#tab=impact

UR - http://webofscience.com/wos/woscc/full-record/WOS:001649019300001

U2 - 10.1002/adfm.202515391

DO - 10.1002/adfm.202515391

M3 - RGC 21 - Publication in refereed journal

SN - 1616-301X

VL - 36

JO - Advanced Functional Materials

JF - Advanced Functional Materials

IS - 32

M1 - e15391

ER -

Modulating Exciton Delocalization in Organic Solar Cells Through Tailored Local Structures and Dipole Offset of Acceptor

Abstract

Funding

UN SDGs

Research Keywords

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GRF: Development of Multifunctional Redox Mediators to Mitigate Halide Segregation in Wide-Bandgap Perovskites for Perovskite Based Tandem Solar Cells

ITF: Innovative Technology and Critical Materials for Developing Flexible Tandem Solar Cells with Ultra-high Specific Power

NSFC-CRS: Integrated Material Design and Device Engineering to Overcome the Limits of Non-radiative Losses and Stability in Next-generation Organic Photovoltaics

Cite this

Modulating Exciton Delocalization in Organic Solar Cells Through Tailored Local Structures and Dipole Offset of Acceptor

Abstract

Funding

UN SDGs

Research Keywords

RGC Funding Information

Access Output

Other Access Options

Permanent Link

Other Files and Links

Fingerprint

Projects

GRF: Development of Multifunctional Redox Mediators to Mitigate Halide Segregation in Wide-Bandgap Perovskites for Perovskite Based Tandem Solar Cells

ITF: Innovative Technology and Critical Materials for Developing Flexible Tandem Solar Cells with Ultra-high Specific Power

NSFC-CRS: Integrated Material Design and Device Engineering to Overcome the Limits of Non-radiative Losses and Stability in Next-generation Organic Photovoltaics

Cite this