The Grätzel Solar Cell

Michael Grätzel created the Grätzel solar cell which is a dye solar cells, compared to the usual solar cells made of silicon. The low energy, non-toxic elements used in the production of these solar cells allows their production to more environmentally conscious in comparison to regular solar cells[1].

Conductive Polymer Dye Sensitive Solar Cell (DSSC) for Improving the Efficiency – Scientific Figure on ResearchGate. Available from: https://www.researchgate.net/figure/The-structure-of-dye-sensitized-solar-cells-DSSCs-23_fig4_328407535 [accessed 28 Mar 2025]

These cells are made of dyes on a porous layer of titanium dioxide, a molecule which can be found in sunscreen for example, though it has a much different use here. Titanium dioxide can work as a semiconductor, which as you might be able to tell from the name conducts electricity some of the time, it needs an extra push of energy to start conducting unlike conductors. The titanium dioxide layer is made up of very small particles which are on the nanoscale (x10^-9 m), since they are so small they have a much larger surface area to volume ratio than a larger particle or solid[2]. This large surface area allows for more of the dye molecules to attach or in other words adsorb to the particle’s surface. The more dye molecules present the more energy the cell can produce as the energy comes from sunlight hitting the dye molecules.  The electrons in this molecule then gains this energy, getting excited to a higher energy level and transferring into the titanium dioxide and this provides that push of energy needed to start conduction in the titanium dioxide. This energy can move through the now conducting titanium dioxide to a circuit which generates electricity.

credit: 2022 EPFL/Alain Herzog – CC-BY-SA 4.0

This is all well and good as a concept but what is the reality of the situation and is this idea viable? As a product I feel it has a lot of good selling points, they are cheap to produce and they are transparent which means they can be used in many ways that traditional solar cells cannot. These solar cells can double up as windows and decorations both indoors and outdoors, depending on the dye used different colours can be achieved even colourless options are available. The Grätzel cells can be seen in the image above of the Swiss Tech Convention Centre during construction. Clearly they are an asset not only for their energy production but also their design unlike the eyesore that the silicon solar panels can be.

The efficiency of these solar cells are up to 15% in direct sunlight and 30% in ambient light conditions[3]. The maximum efficiency of silicon solar cells in direct sunlight is about 25% so the Grätzel solar cell still has a way to go, however since its efficiency can be increased by optimizing the dyes used, the cells can be more efficiently improved then traditional solar cells, where they might have to completely change methods of making these cells for a slight improvement of efficiency. In contrast the dyes of the Grätzel solar cells can be simply switched during improvements of the solar cells.

The Grätzel solar cell is an innovative and favourable renewable energy source that does not come at the cost of debeautification of our environment unlike some other renewable energy sources such as traditional solar cells. While it is not yet commercially available due to testing of the quality and stability of the product, it is a promising energy source for the future.

[1] Aron, Jacob. “Michael Grätzel: Give People Access to Cheap Solar Power.” The Guardian, 3 July 2010, www.theguardian.com/technology/2010/jul/04/michael-gratzel-bright-idea-energy.

[2] Schwartz, Ariel. “Michael Grätzel’s Solar Cells Get Stylish with Color and Translucent Materials.” Fast Company, 21 June 2010, www.fastcompany.com/1661787/michael-grätzels-solar-cells-get-stylish-color-and-translucent-materials. Accessed 28 Mar. 2025.

[3] Papageorgiou, Nik. ““Grätzel” Solar Cells Achieve a New Record.” Actu.epfl.ch, 27 Oct. 2022, actu.epfl.ch/news/gratzel-solar-cells-achieve-a-new-record/.

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