Photoelectric Effect vs. Photovoltaic Effect

Main Difference

The main difference between the Photoelectric Effect and Photovoltaic Effect is that during the Photoelectric Effect, electron emission takes place in open space, whereas during the Photovoltaic Effect, electrons enter into another material.

Difference Between Photoelectric Effect and Photovoltaic Effect

Comparison Chart

Photoelectric Effect vs. Photovoltaic Effect

The photoelectric effect is the process that takes place when light interacted with a substance and causes the discharge of electrons from its surface. On the other side, the photovoltaic effect takes place when the interaction of light on two dissimilar objects causes the production of electrical voltage.

In 1905, Albert Einstein was the first who presented the idea of the photoelectric effect. On the other side, the idea of the photovoltaic effect was introduced in 1839 by A. E. Becquerel, who was a French Physician. The photoelectric effect is more difficult to occur as compared to the photovoltaic effect. As a result of the incident light, the photoelectric effect releases electron in the open space. On the flip side, the photovoltaic effect causes the movement of electrons in different materials.

The photoelectric effect can observe in a cathode ray tube with the involvement of an anode and a cathode attached to an external circuit. On the other hand, the photovoltaic effect takes place between two different metals that combined in a solution. The photoelectric effect does not generate an electric current, while; photovoltaic effect causes the generation of electrical current.

There is no junction potential in the photoelectric effect, whereas, in the photovoltaic effect, the emitted electrons pushed via the junction potential. So, the photoelectric effect occurs when the photons provide enough energy to overcome the electron binding energy. On the flip side, the photovoltaic effect takes place when the photons provide enough energy to overcome the potential barrier of excitation.

During the photoelectric effect, the kinetic energy of emitted electrons is very important, whereas it does not have any importance during the photovoltaic effect. The photoelectric effect is used in imaging technology, studying nuclear processes, giving theoretical information about the shift of electrons between different energy states in atoms. On the other side, solar cells work on the concept of the photovoltaic effect.

What is the Photoelectric Effect?

The photoelectric effect is a process in which the interaction of light with a substance causes the emission of electrons from its surface. Here interaction of light means a ray of light that strikes with a substance or a surface. This idea of the photoelectric effect was first of all given by Albert Einstein in 1905.

While experimenting with this effect, Albert Einstein proposed that when light strikes on a surface of a substance or metal, the electrons in the substance absorb energy and release in the free space by leaving the substance. This happens because the light has a level of energy higher than a specific threshold level. This threshold value is known as the ‘work function’ of the particular substance or metal.

The threshold level is the minimum or slightest energy that is essential to free an electron from its shell. The energy other than this level will transform into the kinetic energy of the electron. This kinetic energy will allow the electron to move freely after being released. So, if the energy provided is equal to the work function only, it will cause the emitted electrons to remain on the surface of the metal. They will be unable to move due to the absence of kinetic energy.

Light is not constant like a wave; it originates in isolated energy packets that recognized as ‘quanta.’ So, light has the ability to send each energy quanta to separate electrons, making them push out of their shell.

Moreover, if the metal placed in a vacuum tube as a cathode with a receiving anode on the other side along with an external circuit, then the emitted electrons from the cathode will be attracted to the anode, which retained at a positive voltage. So, a current is transmits within the vacuum and completes the circuit. This finding of Albert Einstein won him the Nobel Prize for Physics in 1921.

The photoelectric effect is used in imaging technology, studying nuclear processes and for giving theoretical information about the transition of electrons between different energy states in atoms, etc.

What is Photovoltaic Effect?

The photovoltaic effect is the process in which interaction of light with two dissimilar objects causes the production of electrical voltage. It causes the generation of electric current and voltage in the material. Such a current is known as photocurrent. The idea of this effect was presented in 1839 by a French Physician named A. E. Becquerel. He found this concept when he was trying to generate a current between two plates of gold and platinum.

When he immersed gold and platinum in a solution, and they exposed to light, the electrons in the valance band of the metal absorbed the energy from the light and get excited. These excited electrons hopped to the conduction band and became free to move. These high energy or excited electrons then accelerated by a built-in junction potential known as Galvani Potential. This potential help them cross directly from one material to the other.

This movement of electrons is easy as compared to crossing a vacuum space in the photoelectric effect. So, a photovoltaic effect is easy to occur as compared to a photoelectric effect. The solar cells and semiconductors work on this principle.

Conclusion

The above discussion summarizes that the photoelectric effect is the effect in which incident ray of light increases the energy of electrons and causes their free movement in open space. On the flip side, in photovoltaic effect incident light ray provides the energy to the electron to move from one substance to another and causes the generation of current.