[E&E seminars] Tomorrow - Predictive Defect Engineering for Scalable Photovoltaics at $1/Wp - Tonio Buonassisi

[MIT Energy Initiative]

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Predictive Defect Engineering for Scalable Photovoltaics at $1/Wp

Tonio Buonassisi

Photovoltaics Research Laboratory Department of Mechanical Engineering
and Laboratory for Manufacturing Productivity, MIT

Tuesday, November 9

4:15 PM Refreshments to follow  Room 66-110  Abstract

At $1 per peak watt installed cost, solar photovoltaics is projected to
be cost-competitive with traditional fossil fuels in many markets
across the United States. To meet this cost target and ensure scalable
production, thin low-cost materials must be used. Herein lies an
important trade-off: Low-cost materials are typically defect-rich, and
defects impede electronic transport and photoconversion efficiency.
Since efficiency and cost are inversely related, defect-rich materials
have until recently resulted in poor-quality, economically
uncompetitive solar cells.



In this presentation, we explore a path towards low-cost,
high-performance, and scalable photovoltaic absorbers. We introduce the
concept of "defect engineering," the science of controlling defects to
engineer desired material properties. We review recent successful
applications of defect-engineering technologies to traditional ingot
multicrystalline silicon that have led to cell efficiencies above 16%.
Accurate identification of performance-limiting defects requires
multiscale characterization, evaluating cm-size devices and probing
down to the nanometer scale for defect recognition. We will review
recent advances in macroscopic CCD-based PV device characterization
tools, and elucidate how these can be coupled to synchrotron-based
nanoprobe techniques to characterize chemical natures and distributions
of performance-limiting defects less than 20 nm in diameter. Once the
natures and underlying physical behavior of these defects are known, an
opportunity exists to engineer these defects - aided by predictive
modeling - to enhance solar cell performance.



We then consider candidate PV materials with cost-reduction and scaling
potential to support $1/Wp installed costs, yet which are currently
defect-limited: Hyperdoped silicon, with a modified silicon band
structure and potential to exceed the Shockley-Queisser efficiency
limit; tin-sulfide (SnS), a potential Earth-abundant replacement for
CIGS; and cuprous oxide (Cu2O), a potential silicon superstrate for
high-efficiency heterojunction devices.



About the speaker



Tonio Buonassisi, assistant professor of Mechanical Engineering at the
Massachusetts Institute of Technology, heads an interdisciplinary
laboratory focused on photovoltaics (solar energy conversion into
electricity). Prof. Buonassisi completed his Ph.D. at UC Berkeley, with
research at the Fraunhofer Institute for Solar Energy Systems and the
Max-Planck-Institute for Microstructure Physics. Following his Ph.D.,
Prof. Buonassisi became a crystal growth research scientist at
Evergreen Solar, Inc., where he spearheaded efforts to improve solar
cell efficiency and yield, and helped to develop the Quad furnace
platform. Aside from teaching classes focused on PV technology, Prof.
Buonassisi is an author of 65 journal, conference, and workshop
articles focused on PV, and has delivered over 51 invited talks and
plenary/oral presentations on his work throughout the world. Prof.
Buonassisi's research has resulted in several industrial collaborations
and a start-up company. His work has been honored with awards including
the European Materials Research Society Young Scientist Presentation
Award, the German Academic Exchange Service (DAAD) Graduate Research
Fellowship, and the National Renewable Energy Laboratory Graduate
Student Award.



The Seminar Series is made possible with the generous support of
IHS-CERA




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