Probing Nanoscale Carrier Dynamics in P3HT Blended with a Non-Fullerene Acceptor: Impact of Mixing on Device-Relevant Carrier Generation
7 affiliations
- 1Chemistry and Nanoscience Center
- 2National Laboratory of the Rockies
- 3Chemistry Department
- 4Colorado School of Mines
- 5Department of Electrical, Computer, and Energy Engineering
- 6Department of Physics, and ◊ RASEI
- 7University of Colorado
Abstract
High-performing organic photovoltaics (OPVs) rely not only on the appropriate energetics and interfaces for separating excitons into charges, but on distinct areas of donor-rich and acceptor-rich domains to transport those charges to electrodes once separated. In this work, we study a bulk heterojunction (BHJ) of well-studied poly(3-hexylthiophene-2,5-diyl) (P3HT) and a non-fullerene acceptor with an A1-D-A2-D-A1 motif, octyl rhodanine-thiophene-benzothiadiazole-thiophene-octyl rhodanine (ORTBT). Using device characterization and time-resolved spectroscopic techniques, we show that despite promising picosecond photophysical properties P3HT:ORTBT blends do not lead to long-lived charges due to overly-imbalanced mixing between the ORTBT acceptor and P3HT donor on length scales that are either too small or too large. We compare results with a prototypical BHJ, P3HT and PC61BM fullerene to understand the photophysical differences in the exciton dissociation dynamics. The significant mixing in P3HT:ORTBT disrupts the crystalline regions of the P3HT that are necessary for effective hole transport. This work demonstrates the need to consider both the chemical and physical properties of non-fullerene acceptors to achieve an optimal balance of donor-acceptor mixing that facilitates high exciton dissociation efficiency and long-lived carrier transport pathways in the bulk.
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BibTeX
@misc{larson2026probing,
title = {{Probing Nanoscale Carrier Dynamics in P3HT Blended with a Non-Fullerene Acceptor: Impact of Mixing on Device-Relevant Carrier Generation}},
author = {Bryon W. Larson and Melissa K. Gish and Unsal Koldemir and David P. Ostrowski and Kathryn A. O’Hara and Sean E. Shaheen and Alan Sellinger and Michael L. Chabinyc and Nikos Kopidakis and Andrew J. Ferguson},
howpublished = {ChemRxiv},
year = {2026},
month = oct,
doi = {10.26434/chemrxiv.15009722/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009722/v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Probing Nanoscale Carrier Dynamics in P3HT Blended with a Non-Fullerene Acceptor: Impact of Mixing on Device-Relevant Carrier Generation
AU - Bryon W. Larson
AU - Melissa K. Gish
AU - Unsal Koldemir
AU - David P. Ostrowski
AU - Kathryn A. O’Hara
AU - Sean E. Shaheen
AU - Alan Sellinger
AU - Michael L. Chabinyc
AU - Nikos Kopidakis
AU - Andrew J. Ferguson
PY - 2026
DA - 2026/10/01
PB - ChemRxiv
DO - 10.26434/chemrxiv.15009722/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15009722/v1
AB - High-performing organic photovoltaics (OPVs) rely not only on the appropriate energetics and interfaces for separating excitons into charges, but on distinct areas of donor-rich and acceptor-rich domains to transport those charges to electrodes once separated. In this work, we study a bulk heterojunction (BHJ) of well-studied poly(3-hexylthiophene-2,5-diyl) (P3HT) and a non-fullerene acceptor with an A1-D-A2-D-A1 motif, octyl rhodanine-thiophene-benzothiadiazole-thiophene-octyl rhodanine (ORTBT). Using device characterization and time-resolved spectroscopic techniques, we show that despite promising picosecond photophysical properties P3HT:ORTBT blends do not lead to long-lived charges due to overly-imbalanced mixing between the ORTBT acceptor and P3HT donor on length scales that are either too small or too large. We compare results with a prototypical BHJ, P3HT and PC61BM fullerene to understand the photophysical differences in the exciton dissociation dynamics. The significant mixing in P3HT:ORTBT disrupts the crystalline regions of the P3HT that are necessary for effective hole transport. This work demonstrates the need to consider both the chemical and physical properties of non-fullerene acceptors to achieve an optimal balance of donor-acceptor mixing that facilitates high exciton dissociation efficiency and long-lived carrier transport pathways in the bulk.
ER -