Nonequilibrium quantum modeling of electron-hole dissociation at the donor-acceptor interface in an organic solar cell
Year: 2026
Type: article
Abstract: Electron-hole pairs in organic photovoltaics can efficiently dissociate although their Coulomb binding energy exceeds thermal energy. Numerous theoretical studies on quantum dynamics show that electron-phonon interaction makes this dissociation possible. Furthermore, out-of-equilibrium phonon effects could generate non-Markovian ratchet effects, making dissociation particularly efficient. However, few models consider an open system, allowing to calculate the dissociation probability and to track the path followed by carriers. We used a two-dimensional quantum model based on the non-equilibrium Green's function formalism. We model the transport of hole injected into a donor, consisting of a network of polymer chains, while the electron left in the acceptor. By increasing the electron-phonon interaction coupling, we obtain dissociation probability values ranging from 0% to almost 90% for the large coupling. The dissociation improvement with coupling is due to the broadening of quantum states, which, in accordance with the uncertainty principle, increases with coupling. This results in hybridization of the states between the polymer chains, allowing a transition from hopping transport to pseudo-band transport. This allows a crossing of the acceptor-donor interface by a ratchet effect and, an efficient ballistic transport once the interface has been crossed. The ratchet effect observed in this work involves phonon emission, followed by delocalization away from the acceptor-donor interface, then phonon absorption. This ratchet effect, which is simply due to the triangular shape of the Coulomb potential well, is Markovian. This provides a new insight into dissociation mechanisms, which can be very efficient, even considering phonon at equilibrium.
Source: Physical Review Applied
DOI: 10.1103/dhqj-4tp1
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7154450079