Difference Between Photoelectric Effect and Photovoltaic Effect

The main difference between the photoelectric effect and the photovoltaic effect is that during the photoelectric effect, the emission of electrons takes place in an open space, while during the photovoltaic effect, the electrons enter another material.

Photoelectric effect vs. photovoltaic effect

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

In 1905, Albert Einstein was the first to present the idea of ​​the photoelectric effect. On the other hand, the idea of ​​the photovoltaic effect was introduced in 1839 by AE Becquerel, who was a French doctor. The photoelectric effect is more difficult to produce compared to the photovoltaic effect. As a result of the incident light, the photoelectric effect releases electrons into open space. On the other hand, the photovoltaic effect causes the movement of electrons in different materials.

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

There is no junction potential in the photoelectric effect whereas, in the photovoltaic effect, the emitted electrons push through the junction potential. So the photoelectric effect occurs when photons provide enough energy to overcome the electron binding energy. On the other hand, the photovoltaic effect takes place when the photons provide enough energy to overcome the excitation potential barrier.

During the photoelectric effect, the kinetic energy of the emitted electrons is very important, while it is of no importance during the photovoltaic effect. The photoelectric effect is used in imaging technology, studying nuclear processes, giving theoretical information about the movement of electrons between different energy states in atoms. On the other hand, solar cells work on the concept of photovoltaic effect.

Comparison chart

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 light interaction means a ray of light striking a substance or surface. This idea of ​​the photoelectric effect was first given by Albert Einstein in 1905.

While experimenting with this effect, Albert Einstein proposed that when light strikes the surface of a substance or metal, electrons in the substance absorb energy and release it into free space as they leave the substance. This happens because the light has an energy level above 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 minimum energy that is essential to free an electron from its shell. Energy other than this level will be transformed into the kinetic energy of the electron. This kinetic energy will allow the electron to move freely after being released. So if the supplied energy is equal to the work function alone, it will cause the emitted electrons to stay on the metal surface. They will not be able to move due to the lack of kinetic energy.

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

Also, if the metal is placed in a vacuum tube as a cathode with a receiving anode on the other side in conjunction with an external circuit, the electrons emitted by the cathode will be attracted to the anode, which is held at a positive voltage. So, a current is transmitted inside the vacuum and completes the circuit. This discovery of Albert Einstein earned him the Nobel Prize in Physics in 1921.

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

What is the photovoltaic effect ?

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

When he immersed the gold and platinum in a solution and exposed them to light, the electrons in the metal’s valance band absorbed the light energy and became excited. These excited electrons jumped into the conduction band and were free to move. These high-energy or excited electrons are then accelerated by a built-in junction potential known as the Galvani potential. This potential helps them to pass directly from one material to another.

This movement of electrons is easy compared to crossing a vacuum space in the photoelectric effect. Therefore, a photovoltaic effect is easy to produce compared to a photoelectric effect. Solar cells and semiconductors work on this principle.

Key differences

1. A process in which the interaction of light with a substance causes the emission of electrons from its surface is known as the photoelectric effect, while a process in which the interaction of light with two different objects causes the production of electrical voltage is known as photoelectric effect. called the photovoltaic effect.
2. Photoelectric effect was firstly introduced by Albert Einstein in 1905. On the other hand, the idea of ​​photovoltaic effect was introduced in 1839 by AE Becquerel who was a French physicist.
3. The photoelectric effect is more difficult to produce. On the contrary, the photovoltaic effect occurs easily.
4. The photoelectric effect releases an electron in the open space after the incidence of light. On the other hand, as a result of the incident light, the photovoltaic effect causes the movement of electrons in the different materials.
5. The photoelectric effect can be detected in a cathode ray tube with the participation of an anode and a cathode connected to an external circuit. On the other hand, the photovoltaic effect occurs between two dissimilar metals combining with each other in a solution.
6. The photoelectric effect does not generate electric current, while the photovoltaic effect causes the generation of electric current.
7. There is no junction potential in the photoelectric effect. On the other hand, in the photovoltaic effect, the emitted electrons are pushed through the junction potential.
8. The photoelectric effect occurs when the photons provide enough energy to overcome the electron binding energy, while the photovoltaic effect occurs when the photons provide enough energy to overcome the excitation potential barrier.
9. During the photoelectric effect, the kinetic energy of the emitted electrons is very important. On the other hand, it has no importance during the photovoltaic effect.
10. The photoelectric effect is used in imaging technology, studying nuclear processes, and to give theoretical information about the transition of electrons between different energy states in atoms, etc. On the other hand, solar cells work on the concept of photovoltaic effect.

Final Thought

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