Device Model Linking Singlet and Triplet Spin-State Properties to Organic Photovoltaic Device Characteristics
Abstract
This work proposes an exciton-kinetics coupled drift-diffusion (EKDD) model that bridges device-level charge transport with singlet and triplet excited-state kinetics. State populations and reversible photophysical transitions are solved self-consistently, enabling transient and steady-state device response calculations. We investigate how LE-CT, CT-CS, and LE-T energy offsets, together with triplet-transfer kinetics, govern charge generation, recombination, voltage loss, and extraction in organic photovoltaics. We identify CT-CS offset as a primary, largely overlooked factor controlling charge generation and voltage loss. A positive offset makes CT3-CS separation exothermic and improves generation, but lowers CS energy and increases voltage loss; a negative offset makes separation endothermic and highly temperature-sensitive. The model reproduces triplet-mediated recombination in PM6:Y6 and material-dependent triplet recycling in D18:NFA blends. We propose design rules for balanced generation and voltage loss via two charge-transfer channels: the LE-CT-CS pathway favors a moderate LE-CT offset of about 0.15-0.20 eV and a weakly exothermic CT-CS offset of about 0.05-0.075 eV; the T-CT3-CS pathway requires the same CT-CS alignment plus a small CT-T offset, no more than about 0.1 eV, corresponding to a recycling factor K greater than about 10^-2, to maintain fast T-to-CT3 recycling. CT-CS alignment is the main determinant of the charge-generation-voltage-loss trade-off, while triplet-recycling kinetics determines whether this balance survives at the device level. This work provides a unified theoretical description from exciton generation to free charge collection, offering a convenient tool for transient and steady-state analysis in organic photovoltaics.
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BibTeX
@misc{du2026device,
title = {{Device Model Linking Singlet and Triplet Spin-State Properties to Organic Photovoltaic Device Characteristics}},
author = {Jun Du and Liming Liu and Jun Yan},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.18022},
eprint = {2610.18022},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.18022},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Device Model Linking Singlet and Triplet Spin-State Properties to Organic Photovoltaic Device Characteristics
AU - Jun Du
AU - Liming Liu
AU - Jun Yan
PY - 2026
DA - 2026/10/13
PB - arXiv
DO - 10.48550/arxiv.2610.18022
UR - https://arxiv.org/abs/2610.18022
AB - This work proposes an exciton-kinetics coupled drift-diffusion (EKDD) model that bridges device-level charge transport with singlet and triplet excited-state kinetics. State populations and reversible photophysical transitions are solved self-consistently, enabling transient and steady-state device response calculations. We investigate how LE-CT, CT-CS, and LE-T energy offsets, together with triplet-transfer kinetics, govern charge generation, recombination, voltage loss, and extraction in organic photovoltaics. We identify CT-CS offset as a primary, largely overlooked factor controlling charge generation and voltage loss. A positive offset makes CT3-CS separation exothermic and improves generation, but lowers CS energy and increases voltage loss; a negative offset makes separation endothermic and highly temperature-sensitive. The model reproduces triplet-mediated recombination in PM6:Y6 and material-dependent triplet recycling in D18:NFA blends. We propose design rules for balanced generation and voltage loss via two charge-transfer channels: the LE-CT-CS pathway favors a moderate LE-CT offset of about 0.15-0.20 eV and a weakly exothermic CT-CS offset of about 0.05-0.075 eV; the T-CT3-CS pathway requires the same CT-CS alignment plus a small CT-T offset, no more than about 0.1 eV, corresponding to a recycling factor K greater than about 10^-2, to maintain fast T-to-CT3 recycling. CT-CS alignment is the main determinant of the charge-generation-voltage-loss trade-off, while triplet-recycling kinetics determines whether this balance survives at the device level. This work provides a unified theoretical description from exciton generation to free charge collection, offering a convenient tool for transient and steady-state analysis in organic photovoltaics.
ER -