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This laboratory practice is intended for undergraduate students of chemistry, physics, biology, and engineering, to illustrate the simple concepts behind dye-sensitized solar cells (DSSCs), and how basic chemistry can be translated into a practical application through the use of microcontrollers. Unlike commercial counterparts, one of the main problems of handmade solar cells is their low efficiency that impedes their use as a power source, making the laboratory practice less appealing to students. In this work, we present a simple alternative application using an open-source microcontroller and a solar cell as a switch to turn the light on and off, depending on the actual lighting conditions in the room.

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Thin-layer diffusion conditions were accomplished on screen-printed electrodes by placing a controlled-weight onto the cast solution and allowing for its natural spreading. The restricted diffusive conditions were assessed by cyclic voltammetry at low voltage scan rates and electrochemical impedance spectroscopy. The relationship between the weight exerted over the drop and the thin-layer thickness achieved was determined, in such a way that the simple experimental set-up designed for this work could be developed into a commercial device with variable control of the thin-layer conditions. The experimental results obtained resemble those reported for the voltammetric features of electroactive soluble species employing electrodes modified with carbon nanotubes or graphene layers, suggesting that the attainment of the benefits reported for these nanomaterials could be done simply by forcing the solution to spread over the screen-printed electrodic system to form a thin layer solution. The advantages of thin-layer voltammetry in the kinetic characterization of quasi-reversible and irreversible processes are highlighted.