ORO, & DAVAO - Ateneo de Manila University

VOLUME VI | NO. 3 | DECEMBER 2010
13
Printable and paintable
Solar Cells
S i l i c o n -
based solar
cells have been
around for
more than 50
years and yet
they are still
not widely
used today,
David So, a researcher for even when
the project, demonstrates p e t r o l e u m -
a DSSC device based energy
cost and demand are rapidly increasing.
This scenario is very much unlike the
computer chip, which was discovered
at around the same time as silicon solar
cells, but whose development had been
quite rapid. Today, computer chips are
ubiquitous in today’s common devices
such as computers, cell phones, displays,
sensors, and many others. Well, the
simplest explanation is that the cost
of silicon used for solar cells remains
too expensive for common folk, and
this is largely attributed to the cost of
manufacturing the material. Thus, one
of the grand engineering challenges
of this century 1 is to make solar cells
affordable. While there are still advances
in improving the efficiencies of siliconbased
solar cells to improve the cost-toefficiency
ratio, there is also widespread
research in alternative types—the newest
are the third-generation solar cells which
are not based on silicon.
At the Chemistry Department of
the School of Science and Engineering,
Dr. Erwin P. Enriquez and his group of
Chemistry and Materials Science and
Engineering students are doing research
on the so-called dye-sensitized solar cells
(dssc). This dssc is a third-gen solar
cell that was discovered by Michael
Grätzel at the Swiss Federal Institute
of Technology in Lausanne in the early
1990’s 2 . This amazing invention, which
has gained much attention and recently
won Grätzel Finland’s 2010 Millennium
Technology Prize, promises to provide a
cheaper alternative to silicon-based solar
cells.
What makes dssc so attractive is the
fact that the fabrication process for this
solar cell can use simple procedures such
as printing or painting—and this makes
it amenable to roll-to-roll printing such
as what is used in the newspaper industry
continued on page 12
Dr. Erwin P. Enriquez
for affordable mass production of solar
cell modules, and one can also imagine a
future where rooftops are painted or glass
panes are laminated with these devices
to harvest the energy from sunlight that
constantly impinges us year-round in the
Philippines. The components of the cells
are also generally cheaper than silicon.
Worldwide research and development
on this device is rapid, and there is a rush
towards finding the right ingredients (or
“ink”) either to improve the efficiency
(currently, the highest reported is 11%
and it is estimated that 15% efficiency
makes it very competitive), to further
lower cost and improve stability.
The dssc works like an electrochemical
cell wherein sunlight is converted into
electricity by the combination of the
dye, nanoparticles of titania (TiO 2
),
and electrolyte in a layered structure
sandwiched between two conducting
electrodes (one of which is transparent
to light). The dye is a colored pigment
that absorbs sunlight thus raising its
energy (it gets “excited”). Analogous
to water that flows from higher level to
lower level, an electron from the excited
dye readily “flows” down into the lower
energy level of the nearby nanoparticles
of titania, which in turn allows the
electron to flow into the external circuit
through the transparent, conducting
electrode. In effect, the device generates
a voltage much like a battery does, that
can generate electrical current, but in
the dssc case, there is no consumption
of any of the chemical components, and
there is continuous electrical generation
on exposure with light.
The research that Dr. Enriquez’s
group is doing consists of making the
inks that could be used in inkjet printing
of the device. Why inkjet printing
“Because, inkjet printing saves ink, and
it can pattern the deposition as well,”
Lance Go, a researcher of the project,
explains. “But we are also considering
other techniques for fabricating the
device, although our focus now is to
innovate on the formulation of the
inks for the different components of
the device: the dye, the titania, or even
the electrolyte. For example, we found
that incorporating a polysaccharide
extracted from Philippine seaweeds can
stabilize the electrolyte or even be used
Inkjet printing of nano-TiO 2
using a common printer
(LEFT), scanning electron
micrograph of micron-sized
droplets of TiO 2
nanoparticles
(LEFT INSET), and a green
nanomaterial that can be a dye
substitute synthesized at the
Ateneo Chemistry Department
(RIGHT).
Potentials of “Lumut”
Microalgae, commonly called
“lumut,” are the primary producers in
bodies of water. They sustain the life of
other of organisms in this habitat. Alson’s
Aquaculture Inc. produces tons of these
microalgae to feed bangus and tilapia.
Lately, the microalgae is being studied
Teresita R. Perez
for its potential for biodiesel production.
We have been conducting experiments
with Chorella vulgaris, Chlorococcum
humicola and Spurina platensis in the
laboratory, where they are stressed to
produce more lipids. These lipids are
potential sources of biofuel.
Ma. Mercedes T. Rodrigo
Building Educational Software with
Cura Personalis
Rosalind Picard of the Massachusetts
Institute of Technology defines affective
computing as “computing that relates
to, arises from, or deliberately influences
emotions.” With this vision in mind, we
at the Affective Computing group of the
Department of Information Systems and
Computer Science (discs) aim to build
systems that are sensitive to student
moods, feelings, and motivations. We
are interested in emotions that are related
to learning—confusion, boredom,
frustration, and engagement. We are
interested in how these emotions express
themselves through student interactions
with intelligent tutoring systems,
educational games and simulations, and
integrated programming environments.
Through the Ateneo de Manila, the
Department of Science and Technology’s
Philippine Council for Advanced
Science and Technology Research
and Development (pcastrd) and the
Engineering Research and Technology
for Development (erdt) program,
the Affective Computing group has
received in excess of p6 million in
funding since 2007. In that time, the
group has developed a track record for
publication in international conferences
and journals and has established linkages
with researchers from Carnegie Mellon
University, Worcester Polytechnic
Institute, the University of Sussex,
the London Knowledge Lab, and the
Laboratorie d’Informatique de Grenoble.
These microalgae are useful as
sources of vitamins and nutriceuticals,
and for removal of heavy metals in
waterways. Spurulina tablets are rich
sources of vitamins and the “Chlorella
growth factor,” which are advertised
as vitamins for children, are obtained
from lumut. Microalgae also have
the ability to absorb excess nutrients
in bodies of water, including heavy
metals such as cadmium, so they can
be utilized for “bioremediation.” These
organisms are being grown in the Algal
Culture Collection of the Department of
Environmental Science.
Most of the group’s findings support
teacher intuition: Students who are
bored tend to stay bored. Students who
are bored, confused, or frustrated are
more likely to engage in off-task behavior
or system misuse or abuse. Students who
are engaged are most likely to score well,
to try more challenging problems, and
solve these problems in a minimum
number of steps.
The work’s contribution is in
quantifying these phenomena and
expressing them in models that a
computer can respond to. Emotions
have to be expressed in numbers—
number of correct items solved, number
of cursor keys pressed, time between
program compilations, number of
errors. As additional input, the group
invested in two brain computer
interfaces—Brainfingers and the Emotiv
Epoc. Brainfingers detects and records
the wearer’s electroencephalogram
(eeg), electromyogram (emg) and
electrooculogram (eog) signals. The
Emotiv Epoc on the other hand semiprocesses
these signals, informing the
software of the wearer’s cognitive and
emotional state, as well as his facial
expressions.
The Affective Computing hopes
to contribute to the design and
development of cognitive or emotional
interventions to help students maintain
productive affective states, improve
achievement, and provide students with
a satisfying learning experience.
Microalgae in the algal culture collection of
the Department of Environmental Science