Electroberries

“Blueberries Solar Panels” is a project started with the intent of producing energy in a sustainable way. We discovered the possibility of building blueberry photovoltaic panels, which were invented in 1991 and were named Grätzel cells and we immediately tought it was an interesting idea.

MATERIALS

• 6 g of TiO2; 
• ethanol; 
• 10 ml of acidic solution; 
• blueberries, blueberry juice, berry tea, red cabbage extract; 
• electrolyte solution 1: potassium iodide KI (0.5 M), iodine I2 (0.05 M); 
• alcohol 
• electrolyte solution 2: potassium iodide KI (0.5 M), iodine I2 (0.05 M); 
• ethylene; 
• glycol; 
• deionized water. 

The materials used are: 

• FTO conductive glass slides; 
• mortar and pestle;
• beaker; 
• funnel and filter paper;
• porcelain crucible; 
• watch glass; 
• glass stirring rod; 
• support rod; 
• 40-50 micron thick tape;
• absorbent paper; 
• pencil; 
• clips. 

Technical equipment: 

• multimeter / galvanometer; 
• muffle furnace;
• lamp. 

• Clean the glass slides with ethanol;
• delicately dry them with a cloth; 
• check which of the two surfaces is conductive with the multimeter;
• arrange the two slides with the conductive side facing up; 
• secure the two slides to the table with tape;
• covering the top by 4-5 mm and laterally by 1 mm;
• place a small amount of suspension (titanium dioxide) across the width and spread it over the entire free surface of the slides with the conductive side facing up, (the suspension layer should be of the same thickness as the tape);
• after a minute, remove the tape and place the prepared slides in a porcelain crucible.

• The muffle furnace, preheated beforehand, will have reached a temperature of 450°C at this point and will be ready to bake the glass slides; 
• place the slides in a porcelain crucible;
• bake in the muffle furnace at 450°C for 30 minutes.

• Squeeze the berries with cheesecloth;
• filter the liquid adding a little deionized water (anthocyanin dye);
• collect it in a watch;
• immerge the glass slide treated with the TiO2-coated side facing down for about 10 minutes; 
• rinse the slide with water; 
• carefully dry it; 
• rinse with ethanol and blot, ensuring that the porous surface is dry;
• place the slide with the stained surface facing up.

• Clean the glass slide with ethanol;
• gently dry it with the cloth, using the technique used for cleaning glasses;
• old the slide by the edges and, using a graphite rod, apply a light layer of graphite over the entire surface of the conductive glass;
• place the slide with the graphite layer facing up.

• Pair the two slides, with the treated and conductive surfaces facing inward;
• secure the two slides together with two small clips; 
• deposit 2 or 3 drops of electrolyte solution on the edge of the device, which will wet the inside layers by capillary action;
• remove excess electrolyte using a cotton swab dampened with acetone.

• attach two alligator clips to the protruding ends;
• connect the negative (graphite) and positive (titanium dioxide) ends to the multimeter.

Create different circuits by connecting multiple panels in series and/or parallel as needed. Place the cell under the sunlight to get better performance.