What Photocurrent Versus Effective Voltage Tells Us About Charge Generation in Organic Solar Cells
Abstract
The photocurrent of an organic solar cell is routinely plotted against an effective voltage and used to extract an exciton dissociation probability, and through it a free-charge generation efficiency. The photocurrent measures neither. Using a drift-diffusion model in which free-charge generation is field independent and losses occur only by bimolecular recombination, we show that the apparent dissociation probability returned by this procedure lies well below unity even for complete dissociation. Across wide variations of carrier mobility and recombination strength it is a single-valued function of the fill factor and coincides with the short-circuit charge collection efficiency, reporting neither the generation yield nor anything about collection beyond what the fill factor already shows. Even for ideal transport the normalised photocurrent saturates below unity at an intensity-independent first-order limit set by recombination of photogenerated carriers with injected equilibrium charge. Applied to four organic solar cells whose generation efficiencies are known independently, the apparent dissociation probabilities track the short-circuit collection efficiency rather than the generation yield. We therefore suggest this construction not be used, particularly in the high-efficiency non-fullerene acceptor systems that are now state of the art.
Related
- Modular and Cost-effective Scanning Photocurrent Microscopy System for Sub-micron characterization of 2D optoelectronic devices
- Phase Angle and Effective Second-Harmonic Generation Coefficient
- A new generation of effective core potentials: Selected heavy 5d and 6p elements
- Rational Design of Low-Dimensional Hybrid Organic/Inorganic Interfaces for Enhanced Second-Harmonic Generation
- Edge photocurrent distribution in luminescent solar concentrators: analytical treatment and solar cell arrangement
BibTeX
@misc{armin2026what,
title = {{What Photocurrent Versus Effective Voltage Tells Us About Charge Generation in Organic Solar Cells}},
author = {Ardalan Armin and Austin M. Kay and Drew B. Riley and Oskar J. Sandberg and Paul Meredith},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.05170},
eprint = {2609.05170},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.05170},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - What Photocurrent Versus Effective Voltage Tells Us About Charge Generation in Organic Solar Cells
AU - Ardalan Armin
AU - Austin M. Kay
AU - Drew B. Riley
AU - Oskar J. Sandberg
AU - Paul Meredith
PY - 2026
DA - 2026/09/04
PB - arXiv
DO - 10.48550/arxiv.2609.05170
UR - https://arxiv.org/abs/2609.05170
AB - The photocurrent of an organic solar cell is routinely plotted against an effective voltage and used to extract an exciton dissociation probability, and through it a free-charge generation efficiency. The photocurrent measures neither. Using a drift-diffusion model in which free-charge generation is field independent and losses occur only by bimolecular recombination, we show that the apparent dissociation probability returned by this procedure lies well below unity even for complete dissociation. Across wide variations of carrier mobility and recombination strength it is a single-valued function of the fill factor and coincides with the short-circuit charge collection efficiency, reporting neither the generation yield nor anything about collection beyond what the fill factor already shows. Even for ideal transport the normalised photocurrent saturates below unity at an intensity-independent first-order limit set by recombination of photogenerated carriers with injected equilibrium charge. Applied to four organic solar cells whose generation efficiencies are known independently, the apparent dissociation probabilities track the short-circuit collection efficiency rather than the generation yield. We therefore suggest this construction not be used, particularly in the high-efficiency non-fullerene acceptor systems that are now state of the art.
ER -