Ion-gated synthetic photosystems

Area of Science:

• Materials Science
• Photochemistry
• Electrochemistry

Background:

• Charge transport in photosystems is vital for energy conversion.
• Understanding ion-gated mechanisms is key to improving efficiency.
• Previous methods lacked control over ion interactions within transport channels.

Purpose of the Study:

• To investigate the role of molecular ion strings in charge-transporting channels.
• To demonstrate enhanced photocurrents and long-distance charge transport.
• To elucidate the mechanism of ion-gated photosystems.

Main Methods:

• Synthesis of ordered naphthalenediimide stacks on indium tin oxide via polymerization.
• Introduction of coaxial ion strings (anions/cations) using orthogonal hydrazone exchange.
• Analysis of photocurrents and charge transport in varying ion compositions and mobilities.

Main Results:

• Partially protonated carboxylates significantly increased photocurrents by promoting charge separation and inhibiting recombination.
• Mobile anions facilitated long-distance charge transport in thick films.
• Inhibited anion mobility (proton hopping) revealed hole/proton antiport as the mechanism for long-distance transport.

Conclusions:

• Ion-gated photosystems are significant for enhanced photocurrents and charge transport.
• Precise control over ion string composition and mobility is crucial for optimizing performance.
• Hole/proton antiport is identified as a key mechanism for efficient charge transport in these systems.