In this blog post, we’ll take a closer look at what DSSCs are and how they address the limitations of conventional solar cells.
Oil has long been a critical energy source for South Korea’s industrial development. However, due to limited reserves, price volatility, and environmental concerns, interest in renewable energy sources has grown. Renewable energy comes in various forms, such as solar, wind, and geothermal, and among them, solar energy—whose installation scale is growing rapidly—is particularly noteworthy. We commonly encounter solar cells in our daily lives through the rectangular panels installed on apartment rooftops or building exteriors. So, how do these solar cells generate electricity?
DSSCs (Dye-Sensitized Solar Cells) are solar cells created using light-sensitive organic dyes and nanotechnology. A DSSC consists of a transparent substrate, electrodes, an external circuit for electron transport, a dye, and an electrolyte responsible for oxidation and reduction. Here, TiO₂ is suitable as a DSSC nanosubstrate due to its porous structure, which provides ample internal space and excellent electron conductivity. Iodides are commonly used as the electrolyte, and materials containing anthocyanins—such as broccoli or sweet potato peels—can be used as the dye. This is because the functional groups on the TiO₂ surface (-O or -OH) react with the functional groups on the anthocyanins through a dehydration condensation reaction, forming a strong bond between the TiO₂ and the dye.
The operating principle of a DSSC resembles the light reaction in plant photosynthesis. Scientifically, when a substance loses an electron, it is said to be “oxidized”; when it gains an electron, it is “reduced”; and when an electron gains energy and moves to an excited state, it is described as having “transitioned from the ground state to the excited state.” In a DSSC, when sunlight enters through the transparent substrate, the dye absorbs the light and excites the electrons. These electrons are injected into the porous TiO₂ and travel through the external circuit to the electrode. As the excited electrons flow through the external circuit, they consume energy to generate electrical energy, and the dye loses electrons, becoming oxidized. Subsequently, the dye is reduced by receiving electrons from the iodide electrolyte, and the iodide is reduced again by accepting electrons returning from the counter electrode via the external circuit. This series of oxidation-reduction cycles continues, generating electricity.
DSSCs offer several advantages over conventional silicon-based solar cells. First, the materials themselves are considered relatively eco-friendly and produce fewer pollutants when disposed of. Second, they operate relatively stably even under dim light or when the substrate is tilted, making them insensitive to changes in orientation or light intensity. In contrast, silicon-based cells exhibit higher conversion efficiency under optimal conditions but tend to show significant efficiency fluctuations when light is insufficient or the angle is incorrect. Third, because they utilize nanomaterials, they allow for the implementation of designs using transparent or curved substrates and dyes of various colors, making them advantageous for various applications such as building exteriors, windows, and automotive exteriors.
However, DSSCs also have limitations that need to be addressed. In terms of maximum conversion efficiency, they are generally lower than silicon-based cells, and concerns have been raised that the iodide electrolytes commonly used may potentially release harmful substances. For these reasons, while immediate commercialization is not yet certain, research to address these issues is actively underway. Examples include the search for dyes containing higher levels of anthocyanins, the design of ideal nano-substrates to increase solar radiation absorption efficiency, and the development of polymer electrolytes that are safer than iodides while offering superior electron transport capabilities.
Furthermore, active research is underway to expand the scope of design applications through attempts to fabricate DSSCs in flexible or transparent forms. When these technologies are combined, various applications—such as integration into building facades, vehicle surfaces, and integrated power generation in everyday structures—could become a reality. Ultimately, DSSCs are garnering attention as a technological alternative that can complement the advantages of silicon solar cells and expand their range of applications.
In summary, a DSSC is a closed electronic circuit composed of a nanosubstrate, electrodes, a dye, and an electrolyte, and the core mechanism of power generation lies in the process where electrons excited by solar energy circulate through the circuit, repeatedly undergoing oxidation-reduction reactions. Currently, commercialization is limited by the need for further advancements in material technology for nanostructure design and optimization to improve absorption efficiency; however, once these technologies are sufficiently developed, we will be able to utilize the infinite benefits of solar energy more efficiently.
Some reports predict that applying DSSCs to building surfaces in the future could replace a portion of the energy used by those buildings. As we observe the gradual improvement of these limitations, it is worth paying close attention to DSSCs.
