Size-dependent electron transfer from atomically defined nanographenes to metal oxide nanoparticles

Area of Science:

• Materials Science
• Nanotechnology
• Photovoltaics

Background:

• Atomically defined nanographenes (NGs) possess tunable energy gaps due to quantum confinement.
• NGs are promising for sensitized solar cell architectures due to their robustness and large surface area.
• Understanding electron transfer (ET) at nanographene/metal oxide (NG/MO) interfaces is critical for solar energy applications.

Purpose of the Study:

• To investigate the relationship between nanographene size and electron transfer dynamics at NG/MO interfaces.
• To elucidate the fundamental mechanisms governing ET from nanographene donors to metal oxide acceptors.

Main Methods:

• Analysis of electron transfer (ET) dynamics at interfaces formed by atomically precise nanographenes (NGs) and metal oxide (MO) films.
• Correlation of NG size-dependent energy gaps (HOMO-LUMO) with ET rates.
• Application of Marcus electron transfer theory to rationalize observed phenomena.

Main Results:

• A clear inverse correlation was observed between nanographene (NG) size and the rate of electron transfer (ET) to the metal oxide (MO) acceptor.
• Decreasing NG size leads to accelerated ET from the NG donating state to the MO acceptor state.
• This size-dependent ET rate can be explained by variations in the donor-to-acceptor interfacial overpotential, linked to changes in the NG HOMO-LUMO gap.

Conclusions:

• The size of atomically precise nanographenes significantly influences electron transfer dynamics at nanographene/metal oxide interfaces.
• Smaller nanographenes exhibit faster electron transfer, a key factor for optimizing solar energy conversion efficiencies.
• The findings are consistent with Marcus electron transfer theory, providing a theoretical framework for designing advanced photovoltaic materials.