Cain Department of Chemical Engineering Seminar
“Making Thin film Solar Cells from Colloidal Nanocrystal Dispersions”
Eray S. Aydil
University of Minnesota, Department of Chemical Engineering and Materials Science
The global installed capacity to generate electricity using solar cells has doubled
every 2.5 years since 1975, an exponential growth similar to the famous Moore’s “law”
which states that the number of transistors on a computer chip doubles every 2 years.
Whether the solar cell industry can maintain this Moore-like growth is an open question.
One of the threats to maintaining this aggressive growth is the low abundance of some
of the elements (e.g., indium and tellurium) that comprise the current thin film solar
cells based on copper indium gallium selenide (CIGS) and cadmium telluride (CdTe).
Copper zinc tin sulfide (Cu2ZnSnS4 or CZTS), copper zinc tin selenide (Cu2ZnSnSe4
or CZTSe) and their alloys (Cu2ZnSn(SxSe1-x)4 or CZTSSe) are promising potential solar
absorber materials for thin-film solar cells. These materials are comprised of earth
abundant elements and can elevate the solar electricity production to terawatt levels
without the concerns associated with the toxicity and low abundance of the elements
in the current commercial thin-film solar cells. A potentially high-throughput and
low-cost approach to making thin polycrystalline CZTSSe films is through annealing
of coatings cast from colloidal dispersions (inks) of CZTS nanocrystals (NCs) in sulfur
or selenium vapor. In this way, the NC coatings are transformed into polycrystalline
films with micrometer size grains, a suitable morphology for making solar cells. The
transformation of the nanocrystal coating to a polycrystalline coating is driven by
the high surface area of the NCs and, consequently, the high total surface energy
of the NC coating. This approach is well suited for high throughput low-cost roll-to-roll
manufacturing. However, many scientific and technical challenges remain. My group
and collaborators are engaged in establishing the fundamental scientific and engineering
principles towards this end. In this talk I will describe our vision, achievements
to date and the remaining challenges.
Friday December 1, 2017
2:00pm
1221 Patrick Taylor Hall
Coffee will be served at 1:30pm