Argonne National Laboratory

Solar Energy Conversion

Top panel: images showing photosynthetic oxygen evolution (bubbles) in artificial and natural leaves. Bottom panel: Examples of components of natural and artificial leaves that are investigated in this research theme, and range from the complexity of natural photosynthetic proteins (right) to minimalistic artificial photosynthetic assemblies composed of discrete modular light-harvesting chromophores linked to molecular catalysts (left).

Top panel: images showing photosynthetic oxygen evolution (bubbles) in artificial and natural leaves. Bottom panel: Examples of components of natural and artificial leaves that are investigated in this research theme, and range from the complexity of natural photosynthetic proteins (right) to minimalistic artificial photosynthetic assemblies composed of discrete modular light-harvesting chromophores linked to molecular catalysts (left).

Research in the Solar Energy Conversion Group addresses the key challenges of understanding how dynamics and yields for photo-induced electron transfer reactions are determined. We study a number of influencing factors, including the atomic and electronic structures of the reactants in their ground and photo-excited states, the electronic character of initial states, and the overall reaction energetics.

We develop hierarchical, bio-inspired photosynthetic assemblies to test concepts for coupling single-electron excited-states of light-harvesting molecules to long-lived charge separation, charge accumulation, and ultimately, multiple-electron, proton-coupled water-splitting and solar fuels catalysis.

The program integrates artificial photosynthetic system design and synthesis with advanced characterization techniques. This combination interrogates structure and dynamics at the atomic scale and correlates these to solar energy conversion function. The program highlights the development of high-resolution and time-resolved synchrotron X-ray spectroscopy and scattering techniques, and multi-frequency electron paramagnetic resonance and ultrafast optical spectroscopies. The combination of advanced synthesis and atomic-scale characterization is used to investigate mechanisms for solar-to-chemical energy conversion at the fundamental level, and to develop first-principle concepts needed for the design of advanced systems for solar energy conversion.

The program has demonstrated the opportunity to combine chemical synthesis with biological synthesis to create biomimetic hybrids with combined chemical and photosynthetic functionalities, and establishes a first-principles, physical-chemical approach for achieving photosynthetic systems with enhanced solar conversion efficiencies.

A distinguishing strength of this program is the combined use of advanced, time-resolved synchrotron X-ray spectroscopy, X-ray scattering, ultrafast transient optical and time-resolved, multi-frequency electron paramagnetic resonance (EPR) techniques and analyses. This combination of approaches has proven to provide unique capabilities for determining ground and excited state structures and function in both natural and artificial photosynthesis.