Important examples include a combination of
ultrafast lasers, scanned probe/near-field
microscopy, and transport measurements; this
combination should (1) allow the integrative
real-time interrogation of photoabsorption and
charge separation/transport with near-atomic
precision and (2) enable the investigation of the
most important step in solar energy conversion
processes in unprecedented detail. The
knowledge obtained in this type of study will
revolutionize the knowledge base necessary for
optimizing existing and future solar energy
conversion systems. The combination of
ultrafast laser with X-ray and neutron
absorption/scattering/diffraction techniques
(both table-top and large facilities) (see
Figure 52) should enable, on the other hand,
in-situ structural resolution of molecular and
material dynamics across the multiple time and
length scales, and will provide critical insight
into both photocatalytic and photosynthetic
processes.
Impact
The new experimental tools mentioned above
and the capabilities afforded by them will play
an essential role in characterizing photovoltaic, photoelectrochemical, and solar fuel systems.
The knowledge gained from these studies will, in turn, enable the critical assessment and
optimization of the performance characteristics of existing strategies of solar energy conversion.
Furthermore, together with new theoretical and computational tools, the new techniques will help
to test and confirm the operation of potentially revolutionary solar energy conversion devices
and will thereby facilitate the development of disruptive new solar energy conversion strategies.
CROSS-CUTTING THEORETICAL TOOLS
Overview
Good candidate systems for effective solar energy utilization are based on physical and chemical
processes occurring on the full range of length and time scales from the electronic atomic to the
macroscopic. Solar energy systems exploit complex phenomena, molecules, and materials, and
their interplay with the system architecture. These two cross-cutting basic scientific themes —
complexity and multi-scale phenomena — make imperative the continual intimate interaction of
experiment and theory, for which new theoretical tools are required to guide and interpret
experiment and assist in the design of molecules, materials, and systems. A further precondition
Figure 52 New experimental tools that allow
the combined structural and functional
characterization of solar energy conversion
systems. (a) Scanned photocurrent (left) and
electroluminescence measurements of
individual nanostructures. (b) Combined
ultrafast laser and X-ray measurements of
photochemical systems.