CLICK: Learn about photovoltaic cell basics and exciting
research that promises the next generation of solar cells:
enables the system-level cost to be reduced.
Development of this technology for commercial deployment in CPV applications is now
under way at Emcore, with the goal to attain
45 percent conversion efficiency by 2010.
“The ultimate cost target for the CPV device
itself is 12 to 30 cents per watt, depending
on concentration ratio, which is fully in line
with the goal of enabling CPV installations
to produce energy for less than 10 cents per
kilowatt-hour without subsidies,” Newman
said. “With these cost constraints, it is clear
that low-cost manufacturing solutions are required in order to make IMM attractive for
als such as metal and glass.
NREL’s partner, HelioVolt Corp. (
helio-volt.net), developed a proprietary processing
system called Field-Assisted Simultaneous
Synthesis and Transfer (FASST) that bonds
the film layers under heat and pressure, forming large-grain CIGS crystals. All temperatures used in the deposition of the liquid inks
are below 200˚C, (392˚F). The entire process
takes only a few minutes, whereas other solar
cell manufacturing requires hours at temperatures 500˚–700˚C higher, as well as time for
vacuum processing, evaporation and other
“The very short processing time, low thermal budget and high material utilization in
hybrid CIGS cells produced by the FASST
process result in a low cost that is sustainable
in the long term, as it is based on a proprietary
technology advantage,” said Louay Eldada,
Ph.D., chief technology officer for HelioVolt. The company’s FASST process is being
scaled up on a 20-megawatt production line in
This simpler, combined approach could
create enough of the flexible PV film to integrate it with windows, roofing, facades and
other structural components. These products
would replace conventional building materials
and turn buildings into small, self-sustaining
R&D Magazine bestowed an Editor’s
Choice Award for the “the most revolutionary
technologies of the year” on the IMM solar
cell and the hybrid CIGS process. Only four
Editor’s Choice Awards were given among the
top 100 technologies in 2008.
“Over the last three decades, researchers
and others have envisioned a time when we
might be able to do something as simple, fast
and inexpensive as constructing our houses
and buildings with PV-coated materials to
provide the electricity the buildings would
need,” said R&D Editor-in-Chief Tim Studt.
“That vision will soon be a reality thanks to
this low-cost solar printing process developed
by HelioVolt and NREL.”
Evolution of the CIGS Cell
The achievement of a 20 percent world-record energy-conversion efficiency by a PV
technology other than silicon is a significant
accomplishment in itself. However, thin-film
copper indium gallium diselenide (CIGS)
PV cells represent more than just a milestone
scientific accomplishment; they are a success story in scientific discovery, innovation
and technology transfer, providing the foundations for an emerging industry. NREL’s
Miguel Contreras, Ph.D., leads the research
in this area.
CIGS cells use extremely thin layers of semiconductor material applied to a low-cost backing such as glass, flexible metallic foils, high-temperature polymers or stainless steel sheets.
Thin-film cells require less energy to make and
can be fabricated by various processes.
This work has generated attention in both
the scientific community and the investment
sector. Through interactions between NREL
and industry players, a nascent industry has
commercialized CIGS, providing real jobs and
new capitalization. It has also spawned various
technological advances, such as electrodeposited and solution-based processing, which
have, in turn, propelled new companies.
David Ginley, Ph.D., leads the NREL team
that developed the proprietary, CIGS ink-based precursor technology used in the hybrid
CIGS manufacturing process, which won a
2008 R&D 100 Award. Hybrid CIGS cells are A New Brand of Partnerships
manufactured in layers by using ink-jet print- The game-changing solar technologies
ing and ultrasonic spraying technology to described above — and many more being
precisely apply metal-organic inks in separate developed — form the backbone of the PV
layers directly into common building materi- conversion technologies R&D activities at
NREL. Our industry and academic partnerships add flesh to the bone.
Among the newest of these partnerships is
the Center for Revolutionary Solar Photocon-version in Colorado, established in 2008 with
Arthur Nozik, Ph.D., as its scientific director.
The center is dedicated to creating revolutionary ways to directly convert the sun’s energy
to pollution-free, low-cost electricity and fuels. It is part of the Colorado Renewable Energy Collaboratory, whose founding institutions are the Colorado School of Mines, the
University of Colorado at Boulder, Colorado
State University and NREL.
The DOE and NREL are also committed
to establishing innovative, manufacturing-specific avenues for working with industry
partners. NREL’s newest laboratory — the
Science and Technology Facility — was
built to foster collaboration among government, university and industry scientists and
engineers to help accelerate the research, development and transition of PV technologies
from the laboratory phase to proof-of-concept
(pilot) manufacturing. A key feature is the
Process Development and Integration Laboratory (PDIL), an 11,400-square-foot (1,060-
square-meter) space that accommodates a
new class of tools for PV deposition (at a scale
of 6 by 6 inches), processing and characterization. The PDIL will provide the largest-known
collection of integrated PV-specific capabilities supporting multiple PV technologies.
With technologies, partnerships and facilities such as these in place, we are ready for the
solar revolution to begin. I have never been
more optimistic about the soon-to-be-realized
impact of solar energy and other renewables.
And my travels and interactions with people
in the United States and abroad show that I
am not alone in my optimism. The effects
we’re seeing of technologies that have been
in the R&D stages for years represent just the
first glimpse of what is possible.
Those of us who have been in and around
the national solar R&D program for the
past three decades recognize that we are at a
unique point in time — and we stand ready to
move into a new era where solar is no longer
considered an “alternative technology” but
instead is “mainstream technology.” When
that occurs, we will know that the solar revolution has taken place. ST