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Solar
Potential of Purely Organic Solar Cells to Reduce the Cost of Photovoltaics
a report by
Joseph Kalowekamo and Erin Baker
University of Massachusetts
In order to combat climate change the world will need to generate a based on work by Smestad et al.
5
and Meyer.
6
These partially organic
very large amount of energy using carbon-free or carbon-neutral cells have many similarities to POSCs.
technologies, estimated by some to be at least 10TW.
1
While there are
a large number of potential technologies that can be brought into play, Materials Costs
only three energy sources have the potential to generate energy on this Table 1 lists the materials that are needed to produce a POSC, and a
scale: nuclear; carbon capture and storage in conjunction with coal; high- and low-cost estimate for each. Here we discuss the basis for
and energy from sunlight.
2
Among these three sources, energy from each estimate. There are a number of alternative semiconductor
sunlight is generally considered to be the most sustainable avenue. materials that can be used in manufacturing POSCs, which are broadly
Among technologies aimed at harvesting the energy of the sun, solar categorised into conducting polymers, dyes, pigments and liquid
photovoltaics (PV) have drawn the most attention. However, the crystals. In this research, we estimated the cost of carbon-60 (C
60
),
worldwide amount of energy supplied by PV and other solar copper and tin phthalocyanines (CuPc and SnPc), which are pigments
technologies is very low. For instance, in 2008 solar sources supplied and conducting polymers, respectively. These materials were chosen
less than 0.02% of the world’s total energy supply.
3
This is due largely because their combination has resulted in the best POSC device so far,
to the high cost of silicon-based PV technologies. achieving 5% laboratory efficiency.
As a result of this, efforts have been made toward the development of In 1996, Meyer estimated electrical interconnections and electrical
potentially less expensive thin-film solar cells (TFSCs). These include contacts combined for DSSCs to be US$5.00/m
2
, which is equivalent to
inorganic cells such as amorphous silicon, cadmium telluride and US$6.80/m
2
in 2008. It is expected that the cost of electrical contacts
copper–indium–diselenide (CIS), as well as cells using organic materials in POSCs will be lower than that of DSSCs because of the thinner cells.
as an essential part of the device. TFSCs have the potential to reduce The thickness of POSCs is typically half that of DSSCs and other TFSCs
material costs and lower the manufacturing costs of PV through such as cadmium telluride (CdTe), hence less of the materials are
simplified design and processing techniques that are not available to used. For this reason, the cost of electrical contacts and electrical
crystalline inorganic semiconductors. Moreover, purely organic solar interconnections for POSCs was estimated to be 50% of US$6.84/m
2
.
cells (POSCs) have additional advantages, including potentially
inexpensive manufacturing based on laser-printing-type technologies We assume that POSCs will use ultra-thin flexible transparent plastic
and a design that allows them to be built into a wide variety of substrates coated with indium tin oxide (ITO). Based on price data
products, such as clothing, paint or roof tiles. However, POSCs are still posted on the Internet by manufacturers/suppliers (the Aldrich
immature and have shortcomings that need to be addressed before catalogue) and manufacturing cost information for TFSCs as reported
they are commercialised, including efficiency, lifetime and stability. by Haynes et al.
7
and Keshner and Arya,
8
we estimated the range of
costs of ITO-coated flexible plastic substrate, as presented in Table 1.
In this article we summarise our findings from a previous article on the For the cost of the protective cover and the sealant, we used the
potential of OSCs to reduce the cost of PV electricity.
4
We estimate estimated cost for DSSCs, which ranges from US$2.90 to US$4.40/m
2
.
materials, processing and overhead costs to gauge the manufacturing Furthermore, we assumed that the cost of packaging material would
costs. We then factor in efficiency to estimate the module cost and be higher for POSCs than for other TFSCs for two reasons: organic
finally convert that into a levelised electricity cost (LEC). Throughout the materials are sensitive to oxygen and water vapour in an outdoor
article we refer to cost estimates for dye-sensitised solar cells (DSSCs) environment, and because of the ultra-thin structure, i.e. the thinner
the cell the higher the packaging cost. Therefore, it was estimated that
the packaging cost would range from a low of US$2.00/m
2
Joseph Kalowekamo is the Principal Energy Officer in the Renewable and Alternative
(as estimated by Zweibel
9
for inorganic TFSCs) to US$3.00/m
2
– a 50%
Energy Division of the Malawi Department of Energy. Between 2006 and 2008 he was a
Fullbright scholar at the University of Massachusetts, Amherst, where he received an MS
increase in cost.
in mechanical engineering.
Process Cost – Capital and Labour
Erin Baker is an Associate Professor of Industrial Engineering and Operations Research Table 2 presents the estimated process costs, which are made up of
in the Department of Mechanical and Industrial Engineering at the University of
capital and labour costs. As can be seen from the table, we have a very
Massachusetts, Amherst. She was a recipient of an National Science Foundation (NSF)
Faculty Early Career Development (CAREER) award in 2007 for work technology research
wide range for the possible capital costs. This is due to a dearth of data
and development and climate change. She has a PhD in engineering economic systems
on this topic. Specifically, we would have liked to estimate the capital
from the Department of Management Science and Engineering at Stanford University.
cost for each step of the manufacturing process separately in order to
E:
edbaker@ecs.umass.edu
estimate the total capital cost, but no data were publicly available at
the time of the research. Therefore, we used two top-down
© TOUCH BRIEFINGS 2010
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