Ingrid Repins talks with
ScienceWatch.com and answers a few questions about
this month's New Hot Paper in the field of
Engineering. The author has also sent along images of
Title: 19.9%-efficient ZnO/CdS/CuInGaSe2 solar cell
with 81.2% fill factor
I;Contreras, MA;Egaas, B;DeHart, C;Scharf,
J;Perkins, CL;To, B;Noufi, R
Journal: PROG PHOTOVOLTAICS, Volume: 16, Issue: 3, Page:
235-239, Year: MAY 2008
* Natl Renewable Energy Lab, MS 3219,1617 Cole Blvd,
Golden, CO 80401 USA.
* Natl Renewable Energy Lab, Golden, CO 80401 USA.
Why do you think your paper is highly
There is a currently a great deal of interest in thin-film photovoltaics.
This interest has been generated by a number of factors, including
improvements in the technology, First Solar's profitability in
manufacturing thin-film photovoltaics, plausible paths to grid parity put
forth by several companies, and increased consciousness of the environment
and security costs of conventional power.
Does it describe a new discovery, methodology, or
synthesis of knowledge?
of CIGS thin film solar cell.
The paper describes a new record power conversion efficiency for thin-film
Would you summarize the significance of your paper
in layman's terms?
Solar cells convert sunlight to electricity. Thin-film solar cells are made
by large-area coating, rather than growing a single crystal, so they can be
cheaper than some older technologies.
How did you become involved in this research, and
were there any problems along the way?
I became involved in this research because I decided when I was twelve that
I was going to solve the world's energy problems, and it turned out to be a
tougher problem than I expected!
The ability of the team at the National Renewable Energy Laboratory to set
records in power conversion efficiency (PCE) and point the way for the
technology is a testament to years of support from the Department of Energy
and hard work from the researchers. There were many difficult problems
solved along the way, each resulting in incremental improvements or
advances in understanding that often occurred without much fanfare.
Where do you see your research leading in the
Recent results leave no doubt that thin films can compete with traditional
crystalline silicon technology in terms of conversion efficiency. Our next
step is to understand the factors related to getting these results onto the
factory floor (for example, rate, process control, and yield).
Do you foresee any social or political implications
for your research?
The research described in the paper is one small piece in the march of
photovoltaics toward grid parity and large-scale energy production.
Large-scale energy generation using photovoltaics of course has numerous
social and political implications: it will change our relationship with the
environment. It will change how power companies manage the grid. It will
change the distribution of wealth and balance of power among countries
involved in generating energy.
Ingrid Repins, Ph.D.
National Centre for Photovoltaics
National Renewable Energy Laboratory (NREL)
Golden, CO, USA
KEYWORDS: CIGS; THIN FILM SOLAR CELLS; RECORD EFFICIENCY; FILL
FACTOR; RECOMBINATION; DIODE QUALITY; SATURATION CURRENT;