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