Exciton dissociation mediated by phonons in organic photovoltaics

Abstract

It is well known that phonons can overscreen the bare Coulomb electron-electron repulsion, turning it into the effective attraction that binds the Cooper pairs responsible for BCS superconductivity. Here, we use a simple lattice model to prove that the counterpart of this is also possible, whereby phonons overscreen the bare electron-hole attraction and may turn it repulsive at short distances, driving exciton dissociation in certain regions of the parameter space. We argue that this phonon-mediated short-range screening plays an important role in the physics of organic solar cell materials (and other materials with strong electron-phonon coupling) and could point the way to new strategies for optimizing their efficiencies.

arXiv comment11 pages, 6 figures

References in corpus (17)

• The Role of Driving Energy and Delocalised States for Charge Separation in Organic Semiconductors
• Green's function of a dressed particle
• Sharp transition for single polarons in the one-dimensional Su-Schrieffer-Heeger model
• Noise-induced quantum coherence drives photocarrier generation dynamics at polymeric semiconductor heterojunctions
• The Green's Function of the Holstein Polaron
• Light Bipolarons Stabilized by Peierls Electron-Phonon Coupling
• Systematic improvement of the Momentum Average approximation for the Green's function of a Holstein polaron
• Momentum average approximation for models with boson-modulated hopping: Role of closed loops in the dynamical generation of a finite quasiparticle mass
• The polaron paradigm: a dual coupling effective band model
• Trapping of three-dimensional Holstein polarons by various impurities
• Impact of quantized vibrations on the efficiency of interfacial charge separation in photovoltaic devices
• Holstein polaron in the presence of disorder
• Phonon-mediated repulsion, sharp transitions and (quasi)self-trapping in the extended Peierls-Hubbard model
• Ultrafast charge-transfer exciton dynamics in C${}_{60}$ thin films
• Exact treatment of exciton-polaron formation by Diagrammatic Monte Carlo
• Strongly bound yet light bipolarons for double-well electron-phonon coupling
• Lattice exciton-polaron problem by quantum Monte Carlo simulations