Extracting Dye from Red Cabbage and Other Plants for a Dye-Sensitized Solar Cell

Red Cabbage
Red Cabbage

Solar Cell Experiment

From past experiences of building a dye-sensitized solar cell, I have to say that there are several important things to note when considering the creation process.

The first step to the experiment is the collection of TiO2 from powdered donuts. A micro spatula is used to scrape off the white powder carefully with as little dough taken as possible. The powder is the only thing wanted.

This powder is then dissolved in boiling water and filtered with a coffee filter. The solid (it's more like a gelatin) is cleaned TiO2 and is kept, and the liquid that filtered through into the beaker underneath is thrown away.

Then this thick goopy mass is deposited into a crucible and fired up to dry it out.

After the drying process is complete, the TiO2 is mixed with acetic acid into a mixture with a consistency of paint.

A small square FTO conducting slide is prepared with 4 pieces of tape around the edges evenly to form guidelines for the application of the extracted TiO2.

Look at guide below to form slide. The dye that is shown in the picture is extracted from plants and will be explained in further detail below the picture.

The TiO2 layer can be applied to the slide in two ways. The first way requires a clump of the TiO2 and acetic acid mixture to be placed on the slide and then carefully and steadily spread across the taped off square with a straight edge. This needs to be as even as possible!

Another way to deposit the TiO2 is by making the solution slightly thinner, dropping a clump into the center of the square and rolling once forward and once backward, using a glass stirring rod as a rolling pin.

At the very bottom of the page, there is a video demonstration showing all the steps to this process (using the rolling pin method).

Preparation of the slide, TiO2 application process, and the dying of TiO2.

Click for larger size.
Click for larger size.

Six Options for Extraction of Dye

There are several different methods of extracting anthocyanins and chlorophyll.

Option 1: The very best option which yields the best results is the boiling of red cabbage in water and application of solely that dye. Red Cabbage has 36 different anthocyanins as well as cholorphyll making it the number 1 contender. The highest reading came in at around 700 mV.

Option 2: Elderberry wine showed great results and came in second place with a voltage aroun 500 mV.

Option 3: Another great option is to use large amounts of cold red cabbage crushed into a small portion of methanol (the more concentrated the better) mixed with a filtered solution from methanol and crushed blackberries, raspberries and blueberries. This results with a voltage around 350 mV.

Option 4: Passion tea from starbucks made from hibiscus plant can be used to conduct a voltage of around 310 mV.

Option 5: Purple corn may be used, but I highly suggest against it as I have not witnessed very high yields from it - around 200 mV

Option 6: Spinach and blackberries mixed in an attempt to combine chlorophyll and anthocyanins (blackberries are rather high in anthocyanins and spinach in chlorophyll). However, this idea did not pan out as well as projected. It ended with a voltage of around 108 mV.

If you have made a solar cell or plan to make one, which option was chosen?

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Mortar and Pestle
Mortar and Pestle

Red Cabbage Process

Now that you know red cabbage is the best choice for extracting dye, there is the decision of what to do with the red cabbage to best extract this dye.

1. You can tear it and boil it in water, then use the purple solution.

2. You can use methanol or ethanol and crush and grind the cabbage with a mortar and pestle.

3. Dealer's imagination

From personal knowledge, it seems that boiling works the best of anything I've seen thus far, although I am sure there are other ways to ensure a high voltage in the end.

Perfect Demonstration: Step by Step

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Comments 4 comments

RTalloni profile image

RTalloni 5 years ago from the short journey

Well now, you've got me thinking too much for this late at night. So many questions come to mind. :) Here's one I have to ask, though I may regret the answer. Are you saying that the powder on doughnuts is not simply white powdered sugar?

Love the red cabbage idea. I'll probably not make a solar cell (unless my grandson asks me to-but he'll get no prompting from me), however, I'm thinking of many other uses for its dye, mainly fabrics and then using it as paint. Thanks for an interesting read.

kassishae profile image

kassishae 5 years ago from Ohio Author

Yes, believe it or not, The Titanium Oxide or TiO2 in powdered sugar is what gives the sugar it's beautiful white color. =) And I am truly happy you enjoyed reading it. =D

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nreyes128 5 years ago

For the elderberry wine, did you concentrate or extract anything or did you just directly apply the wine to the solar cell? Thanks!

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nreyes128 4 years ago

Did you do any extraction or purification to the elderberry wine? Thanks!

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