Solar cell is one of the most promising technologies at this time, because the phenomenon of global warming due to excess carbon dioxide gas in the earth's atmosphere resulting from fossil combustion is one of the most frequently reported problems. If this condition is continued, it will lead to permanent climate change, so that it will change the adaptation patterns of living things related to it.
Figure 1. Solar cell
(source: https://bumninc.com/pembangunan-plts-cirata-dimulai-tahun-depan-solar-panel-terbesar-di-asia-tenggara/)
1. Two different semiconductor layers
In general, semiconductors consist of an n-type capable of producing many electrons, and a p-type capable of absorbing the electrons. A solar cell consists of two semiconductor layers that are bonded directly to each other. The n-type semiconductor layer is generally exposed to sunlight, and the p-type semiconductor layer underneath. In the upper layer of the n-type and the bottom of the p-type connected by fiber cables to capture electrons which will generate an electric current.
2. Depletion layer
The depletion layer is where the n-type semiconductors meet and which are bonded to each other, so that the layer is in the middle between the other two layers. This layer is formed automatically when the two types of semiconductors are connected. The depletion layer can be enlarged by thickening the p-type semiconductor layer and thinning the n-type semiconductor. This concept can be applied by certain methods based on the many developed coating techniques
3. The depletion layer is where the process of generating electric current occurs
The condition in the depletion layer is that the electrons from the n-type semiconductor combine with the holes of the p-type semiconductor, so that an equilibrium occurs to form a neutral layer. When light is exposed to this layer, there will be an excitation of electrons which can be channeled back to the n-type semiconductor layer and captured by the cable fibers to flow the electron to a load (such as light bulbs, dynamos, etc.), and then forwarded to the p-type semiconductor in a closed circuit. This flow of electrons is similar to the electric current generated from a battery.
Figure 2. Electric generating mechanism of a solar cell
(source: https://www.imagesco.com/articles/photovoltaic/photovoltaic-pg4.html)
4. Modification of solar cells to increase the energy produced
As we explained earlier, the depletion layer is where the electrons are generated. The larger the depletion layer, the more electrons are generated. Enlarging the depletion layer can be done very easily, because thinning the n-type semiconductor layer and thickening the p-type semiconductor layer will produce the desired effect. This condition also gives an advantage, where by thinning the n-type semiconductor layer facing towards the light source, the more light is able to reach the depletion layer.
