Quantum coherence controls the charge separation in a prototypical artificial light-harvesting system

Area of Science:

• Artificial photosynthesis
• Photovoltaics
• Quantum effects in chemistry

Background:

• Efficient light-to-electricity/fuel conversion is key.
• Current models assume ultrafast, incoherent electron transfer.
• Biological systems show evidence of quantum coherence.

Purpose of the Study:

• Investigate primary charge transfer in artificial reaction centers.
• Explore the role of quantum coherence in artificial devices.
• Understand photoinduced current generation mechanisms.

Main Methods:

• Femtosecond spectroscopy for high time-resolution.
• Time-dependent density functional theory (TD-DFT) calculations.
• Studied a supramolecular triad as a model system.

Main Results:

• Provided evidence for coherent electron and nuclear wavelike motion.
• Observed this motion on a timescale of tens of femtoseconds.
• Identified the chromophore-acceptor interface as critical for triggering coherence.

Conclusions:

• Quantum coherence is essential for efficient charge separation in artificial systems.
• Wavelike electron-hole splitting is driven by coupled electron-nuclear dynamics.
• Findings challenge traditional views of charge transfer in artificial photosynthesis and photovoltaics.