Introduction to Solar Cells

  1. Need of hour

Currently, fossil fuels are the main energy sources used across the globe. However, fossil fuels not only cause significant environmental pollution, but they are going to be exhausted soon. Hence, we need to look for alternative renewable energy sources to fulfill the growing energy demands of human society. Solar energy is one of the most promising renewable energy sources. Solar light is available in abundance and likely to live forever. the Solar cell is a device that converts solar light into electricity without harmful emissions or generating waste.

2. Working principle

Solar cells generate electrical energy upon exposure to solar light. This works on the principle of the photovoltaic effect which is a physical and chemical phenomenon. When the light is absorbed by a material (typically a semiconductor material with a bandgap less than the incident light photon energy), electron-hole pairs are generated. These generated electrons and holes are collected in an external circuit producing electricity.

Depending upon the type of solar cell, electron and hole collection mechanisms vary. Organic materials are widely used to collect these charge carriers (electrons and holes) in the external circuit. In dye-sensitized and perovskite solar cells, organic materials are used as electron and hole transport materials. In organic solar cells, the organic materials serve a two-fold purpose; generating electron-hole pair upon light exposure, and transporting the electrons and holes to the respective contacts connected to the external circuit.

3. Types of solar cells

Solar cells can be categorized based on different aspects i.e. material, morphology (bulk/thin film, polycrystalline/monocrystalline/amorphous, plasmonic, quantum dot, nanocrystal), single/multijunction, concentrated/non-concentrated, and generation (first/second/third). Some common type of materials used in solar cells are listed below:

4. Applications