Dry Sensitized Solar Cell Lab
Part 1 – Preparing the Titanium Dioxide
Suspension
Step 1: Start with 6 grams of titanium dioxide
powder in a mortar and pestle. Under a ventilated
fume hood, slowly add vinegar in 1 ml increments
to the solution, grinding well each time.
The process should take around 30 minutes
and will result in a very white milky paint-like
solution.
Step 2: Add a drop of clear dishwashing liquid
to the solution but do not grind otherwise
it will get foamy and bubbly. The dish washing
liquid will act as a surfactant which reduces
the surface tension of the solution and thus
helps it coat the glass plates more evenly.
Step 3: Use the funnel to pour the solution
into the small dropper bottle. Leave the solution
alone to equilibrate for at least 15 minutes.
Part 2 – Coating Slide with TiO2 Suspension
Step 1: Clean two conductive glass slides
by rinsing them with a wash bottle filled
with ethanol; gently dry them with a soft
tissue.
Step 2: Use a multimeter set to resistance
- ohms to check which side of the glass side
is conductive. The slide should conduct between
10 and 30 ohms on the conductive side and
nothing on the non-conductive side.
There should be a slight visible difference
between the conductive and non-conductive
slides as well. The conductive side will appear
bluish and cloudy while the non-conductive
side will appear clear and yellowish.
Step 3: Use the transparent tape to tape one
glass slide down on the table on all four
edges. The tape should cover roughly 1 millimeter
of the slide on three of the edges and about
4 millimeters of the slide on the remaining
edge.
This tape has a controlled thickness and will
form a 40 – 45 micron deep channel into
which titanium dioxide suspension can flow.
Step 4: Use ethanol on a tissue to wipe off
any finger prints or oils on the slide.
Step 5: Put a drop or two of the titanium
dioxide solution on the slide and quickly
spread the solution as evenly as possible
over the slide using a clean glass stirring
rod.
Step 6: Wait for the slide to dry for a few
minutes before carefully removing the tape.
Part 3: Annealing the Coated Slides
Step 1: Anneal the titanium dioxide film on
the glass slide in a fume hood or well-ventilated
area. Use one of the following methods:
-One: Make a simple tube furnace from the
hot air gun.
1. Start by removing the outer plastic casing
of the base of the nozzle to prevent it from
melting.
2. Then wrap aluminum foil around the nozzle
to form an enclosed oven.
3. The slide will lie flat inside this oven
for the annealing process. Be sure to leave
a small opening in the foil so that you can
watch the slides for color change as they
anneal.
4. Turn the hot air gun on high or to 450
degrees Celsius. Let heat for 30 minutes.
-Two: Place a ring stand over an alcohol burner.
1. Anneal the slides one by one by resting
them on the ring stand on the tip of the flame
for 10 minutes.
Step 2: Watch the slides as they anneal. The
titanium dioxide coated section should turn
purplish-brown and then back to white as the
heat burns off the surfactant.
Step 3: Store the slides for later use.
Part 4: Staining the TiO2 With Anthocyanin
Dye
Step 1: Use a clean mortar and pestle to crush
3 – 4 berries. Transfer the crushed berries
to a petri dish.
Step 2: Add about a table spoon of distilled
water to the crushed berries and stir with
a clean glass rod.
Step 3: Place the slide faced down into the
berry mixture so that the titanium dioxide
coated section is submerged in berry juice.
Step 4: Let the slide soak in the juice for
10 minutes. The film should be stained bright
purple.
If you can see any white titanium dioxide
remaining on either side of the glass after
10 minutes, put the slide back into the dye
for another 5 minutes.
Now is a good time to start on part 4: carbon
coating the counter electrode.
Step 5: Lift the slide out of the juice using
a pair of plastic tweezers. Rinse the slide
first in distilled water to remove and fibrous
debris from the berries and then in ethanol
to remove excess water from the porous titanium
dioxide coated section. Let the slide dry
with a tissue.
Step 6: You have now made a titanium dioxide
dye-sensitized electrode. If the slide is
not going to be used right away, store it
submerged in distilled white vinegar in a
closed dark-colored bottle.
Part 5: Carbon Coating the Counter Electrode
Step 1: While the titanium dioxide electrode
is being stained in the berry juice, make
the counter electrode from another piece of
conductive glass.
Step 2: Light a tea candle with a match.
Step 3: Determine which side of the clean
glass plate is conductive with a multimeter
set to resistance - ohms. Hold the slide by
one edge with metal tongs.
Pass the conductive side through the middle
of the flame until the entire side is coated
evenly with soot, except where the metal tongs
were.
Step 4: Place the carbon coated slide face
up on the counter. Be careful the slide with
be hot. Allow it to cool.
Then use a tissue and cotton swab to clean
any residual soot off the edge of the slide
covered by the metal tongs to clear the carbon
off of a 4 millimeter strip. This edge will
be where the alligator clip attaches.
Step 5: You have now made a carbon coated
counter electrode. The carbon coating on the
slide is very fragile and is easily rubbed
off. Be careful not to touch it.
Part 6: Assembling the Solar cell device.
Step 1: The stained titanium dioxide glass
slide has been stored in vinegar. Carefully
remove it. Rinse the slide with water and
then with ethanol. Then gently blot it with
a tissue.
Step 2: These two slides, the titanium coated
slide and the carbon coated slide, will be
sandwiched together to make a solar cell.
Both slides have a 4 millimeter strip on one
edge that is clear of any coating. The slides
must be assembled so that the coated areas
of the slides are touching each other completely.
This means the slides will be offset and the
4 millimeter empty strips will be exposed
on each side. These 2 exposed edges will serve
as the contact points for the negative and
positive electrodes.
Step 3: Place the dry titanium dioxide coated
slide on a flat surface so that the titanium
dioxide coated section is faced up. Place
the carbon coated slide faced down on top
of the titanium dioxide slide so that the
coating completely covers the titanium dioxide
coating, leaving a 4 millimeter strip exposed
on each slide.
Step 4: Pick up the two slides in this orientation
being careful to not let them move. Clip the
edges, the ones that do not have the 4 millimeter
strip exposed together on both sides with
two binder clips.
Step 5: Place one or two drops of the iodide
electrolyte solution at one of the edges of
the slides.
Step 6: Alternately, open and close each side
of the solar cell by releasing and returning
the blinder clips. The liquid is drawn into
the space between the electrodes by capillary
action. This wets the stained titanium dioxide
film. Make sure that all of the stained area
is contacted by the electrolyte.
Step 7: Wipe off the excess electrolyte solution
from the exposed areas of the glass using
cotton swabs and tissue dampened with ethanol.
The cell will not work well if there is any
electrolyte solution left on the exposed areas
were the alligator clips are attach.
Step 8: Fasten alligator clips to the two
exposed sides or poles of the solar cell to
make electrical contact to the finished device.
Part 7: Measuring the Electrical Output
Step 1: The completed solar cell can be taken
outside and measured under sun light. The
cell will last longer if it is protected from
the elements by a polycarbonate plastic cover
like a plastic petri dish. Sun and air will
dry out the iodine electrolyte solution inside
the cell which will speed up the deterioration
of the dye molecules in the berry juice.
Step 2: For more instructions on how to measure
the voltage and amperage of the cell, see
Experiment 1: Measuring Voltage and Current.
