Department of Physics and Astronomy, University of Denver
Materials Department, University of California, Santa Barbara
Department of Chemistry & Geochemistry , Colorado School of Mines
Supramolecular Non-Fullerene Electron Acceptors for Organic PVs – A Pathway Toward 20% Efficient Cells
A Scialog-funded collaborative research team of Sean Shaheen, associate professor of physics, University of Denver; Alan Sellinger, associate professor of chemistry, Colorado School of Mines; and Michael Chabinyc, associate professor of materials science, University of California, is exploring innovative ways to greatly reduce costs while improving the efficiency of photovoltaics, the production of electricity from solar panels. The team is working toward one day creating solar cells that produce electricity below current U.S. government targets of 50 cents per watt for photovoltaic module costs. To do this, the three collaborators are taking a bold approach aimed at creating what are called organic bulk heterojunction (BHJ) photovoltaics. Basically, those words refers to chemical compounds incorporating carbon and hydrogen (elements found in living organisms, hence “organic”) that can be produced in bulk (rather than on the extremely tiny nanoscale) and which feature an interface, or distinct boundary – a heterojunction—that occurs between two layers or regions of dissimilar crystalline material – in other words, semiconductors.(A semiconductor, the basis of modern electronics, is a compound that conducts electricity under some conditions but not others.) Today’s high-efficiency organic photovoltaic devices use fullerenes—any of various cage-like, hollow molecules composed of hexagonal and pentagonal groups of atoms that constitute the third form of carbon after diamond and graphite. But fullerenes don’t lend themselves to bulk production processes and are therefore expensive to make and purify. In addition, they are not great absorbers of visible light, the main source of photovoltaic energy. To overcome these limitations and other technical speed bumps the collaborators are exploring new and inexpensive processes to improve key molecular structures and functions within BHJs. They hope to improve these materials’ dielectric constant, or the amount of electrostatic energy that can be stored in terms of positive and negative charge, as well as to rearrange molecules to improve the transport and control of electrons to create a current.
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