Photochemistry is the study of chemical processes that are driven by light (photons). In solar cells, light energy from the sun is converted into electrical energy — and photochemistry plays a key role in making that possible.
Role of Photochemistry in Solar Cells:
- Light Absorption
- When sunlight hits a solar cell, the material inside (like silicon, perovskites, or organic dyes) absorbs photons.
- Photochemistry explains how these photons excite electrons from a lower energy state to a higher one.
- Exciton Formation and Charge Separation
- The absorbed light creates electron-hole pairs (called excitons).
- Photochemistry helps us understand how these excitons separate into free charges — electrons and holes that can move in opposite directions.
- Electron Transport
- Electrons travel through the semiconductor material to the external circuit.
- Photochemistry guides the design of molecules and materials that allow electrons and holes to move efficiently without recombining too early.
- Design of Light-Active Materials
- Photochemistry is used to design and optimize new materials (like dye-sensitized solar cells or organic solar cells) where special molecules capture sunlight more efficiently.
- For example, synthetic dyes are engineered to absorb more of the solar spectrum.
- Stability and Efficiency
- Photochemical principles help researchers understand degradation caused by light and heat, leading to longer-lasting solar cells.
Example: Dye-Sensitized Solar Cells (DSSC)
- A dye molecule absorbs sunlight (photochemistry at work).
- Excited electrons are injected into a semiconductor (like TiO₂).
- This process converts light into electrical current.
In short: Photochemistry provides the fundamental knowledge of how light interacts with materials, which is crucial for designing efficient, stable, and cost-effective solar cells.