Do ultrafast exciton-polaron decoherence dynamics govern photocarrier generation efficiencies in polymer solar cells?

Abstract

All-organic-based photovoltaic solar cells have attracted considerable attention because of their low-cost processing and short energy payback time. In such systems the primary dissociation of an optical excitation into a pair of photocarriers has been recently shown to be extremely rapid and efficient, but the physical reason for this remains unclear. Here, two-dimensional photocurrent excitation spectroscopy, a novel non-linear optical spectroscopy, is used to probe the ultrafast coherent decay of photoexcitations into charge-producing states in a polymer:fullerene based solar cell. The two-dimensional photocurrent spectra are interpreted by introducing a theoretical model for the description of the coupling of the electronic states of the system to an external environment and to the applied laser fields. The experimental data show no cross-peaks in the two-dimensional photocurrent spectra, as predicted by the model for coherence times between the exciton and the photocurrent producing states of 20\,fs or less.

References in corpus (6)

• The Role of Driving Energy and Delocalised States for Charge Separation in Organic Semiconductors
• Multidimensional Coherent Photocurrent Spectroscopy of a Semiconductor Nanostructure
• Direct observation of ultrafast long-range charge separation at polymer:fullerene heterojunctions
• Noise-induced quantum coherence drives photocarrier generation dynamics at polymeric semiconductor heterojunctions
• Spin-dependent electron-hole capture kinetics in conjugated polymers
• Spin-Boson Model with Diagonal and Off-Diagonal Coupling to Two Independent Baths: Ground-State Phase Transition in the Deep Sub-Ohmic Regime

Cited by in corpus (10)

• Incoherent population mixing contributions to phase-modulation two-dimensional coherent excitation spectra
• Photonics and Spectroscopy in Nanojunctions: A Theoretical Insight
• Coherent multidimensional spectroscopy in the gas phase
• Frenkel biexcitons in hybrid HJ photophysical aggregates
• Identifying incoherent mixing effects in the coherent two-dimensional photocurrent excitation spectra of semiconductors
• A model for exciton-polaritons in uniaxial molecular crystals describing spatial dispersion, refraction and reflection
• Probing polaron excitation spectra in organic semiconductors by photoinduced-absorption-detected two-dimensional coherent spectroscopy
• Hubbard NEGF Analysis of Photocurrent in Nitroazobenzene Molecular Junction
• Resolving nonlinear recombination dynamics in semiconductors via ultrafast excitation correlation spectroscopy: Photoluminescence versus photocurrent detection
• QuDPy: A Python-Based Tool For Computing Ultrafast Non-linear Optical Responses