Blackberry Textile Solar Cell


Inspired by blueberry solar cell projects, such as ‘Temporary photoElectric Digestopians [TpED]‘ by Bartaku and …., we decided to try to build our own blueberry solar cells.

We found these instructions on internet, and tried to follow…

So, what we understood is that you need to make layers of:
-Glass with conductive layer (Transparent electrode)
-Titanium Dioxide
-Raspberry (or Blueberry, Blackberry, Blackcurrant..)
-iodide solution
-Glass with conductive layer (electrode)

The first problem we had was that we do not have glass with conductive layer on. But we had a good idea. One of the conductive fabric Maurin brought is a thin silk organza with silver thread. It is half transparent and let the light go through. We decided to use this fabric instead of the glass and try to make the entire solar cell out of fabric.
This organza fabric contains silver thread only on weft side. The warp is a very thin silk thread. Therefor it is only conductive on the weft direction. To make the fabric conductive on both direction, we sew one line of conductive thread (Elitex) on warp direction with sewing machine.

The second problem is that we do not have titanium dioxide. But I googled it, and found out that it is same as titanium white pigment, a common color in painting >>
We were lucky to remember that there is a painter’s atelier at Paillard. We visited her to see if she can borrow us some titanium white pigment. ! super lucky, she had a right pigment and was very nice to let us use it.

We have screen printed the titanium white pigment onto the organza conductive fabric. As the pigment is a powder, we needed to mix it with some kind of medium to screen print.
We first tried with textile binder, but we were afraid that the textile binder will isolate the pigment and prevent it to touch the conductive fabric. So, we also tried with our self-made printing medium of Gum Arabic + Lubricator Gel.
Titanium White Pigment from the painter

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Silkscreen printing titanium white with Gum Arabic

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Making a mixture of copper paint + titanium white for silkscreen printing

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Printed results

The next layer is the raspberry in this tutorial. We found wild blackberry growing next to the water outlet. We picked some and smashed it in a glass bowl.
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Now again, we had a problem. What is “iodide solution”?! We ask our expert, Lucie, and she said it is something that allow the electron to travel, like salt water. So we made our iodide solution with kitchen salt and Lubricator Gel. Let cotton fabric to soak this gel and we are good to go. Now the cotton fabric is slightly conductive, which means electron can flow.

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Well, maybe you wonder why we are using lubricator gel. It is pH neutral and can keep moist as it is in the gel form, perfect for our purpose. Don’t ask why we had this around though…

The last layer is graphite (carbon) with conductive material. We printed Bare conductive ink on Statex silver conductive fabric as our first trial. We later noticed Bare ink is a problem as it starts to melt into the gel. We decided to use Eeonyx carbon enforced non-woven fabric as graphite + electrode layer.
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Here is the construction of layers:
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Paint the mashed blackberry juice onto the titanium white layer on the organza conductive fabric

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Apply the cotton with iodide solution layer

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Then add the Bare conductive (carbon) with silver conductive fabric layer. Make sure to lay the carbon side to the iodide solution

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Then we pressed the layers together by rolling a glass bottle couple of times. This is to make sure the layers are touching well.

Now flip the constructed layers so the transparent organza conductive fabric side faces the sun light

And here is the result of our first attempt..

.. well, it does not really produce electricity with sunlight unfortunately