Why is it appropriate to think of a photovoltaic cell as an

Why is it appropriate to think of a photovoltaic cell as an LED operating in reverse? Is there a \"best\" material to be used for a solar photovoltaic? Please discuss some of the pro\'s and con\'s of a few materials from a scientific perspective, including words like energy gap and spectrum).

Solution

Photovoltaic cells as well as LEDs (Light emitting diodes) both are pn junction diodes that work in reverse bias and forward bias respectively. The photovoltaic cells work on the principle of conversion of electrical energy into light energy while LED work on the principle of conversion of light energy into electrical energy . Thus, when a LED is connected in reverse bias it acts as a photovoltaic cell.

Gallium Arsenide (GaAs) is a very good material as a photovoltaic cell with a high efficiency.

While selecting the materials for photovoltaic cells we should first consider the enrgy gap of the material. Lower the energy gap better the material is suited for the purpose of generation of electricity by method of photovoltaic effect.

Energy gap is the energy required to free an electron which can participate in conduction of electricity inside a semiconductor. Crystalline Silicon is one suitable material from scientific perspective which has a band gap of 1.1 eV , CIS and CdTe (1.5eV energy gap at 300K) are some other good materials amongst polycrystalline materials. Also, GaAs which has a lowest band gap 1.39 eV at 273 K is high efficiency material for this purpose. It has a direct band spectrum.