Physics

Difference between photoelectric effect and photovoltaic effect

The photoelectric effect produces free electrons (charges) and the photovoltaic effect produces electric current thanks to those free electrons released through the photoelectric effect or process. 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.

Key differences

  • 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 called the photovoltaic effect.
  • The photoelectric effect is more difficult to produce. On the contrary, the photovoltaic effect occurs easily.
  • 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 different metals that combine with each other in a solution.
  • 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.
  • 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.
  • The photoelectric effect was first presented by Albert Einstein in 1905. On the other hand, the idea of ​​the photovoltaic effect was presented in 1839 by AE Becquerel, who was a French physicist.
  • The photoelectric effect releases an electron into 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.
  • The photoelectric effect does not generate electrical current, while the photovoltaic effect causes the generation of electrical current.
  • The photoelectric effect occurs when photons provide enough energy to overcome the electron binding energy, while the photovoltaic effect occurs when photons provide enough energy to overcome the potential excitation barrier.
  • 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.

Difference between photoelectric effect and photovoltaic effect in Tabular Form

photoelectric effectphotovoltaic effect
DefinitionA process in which the interaction of light with a substance causes the emission of electrons from its surface is known as the photoelectric effect.A process in which the interaction of light with two different objects causes the production of electrical voltage is called the photovoltaic effect.
IdeaThe photoelectric effect is more difficult to produce.This effect is easy to produce.
HistoryThe photoelectric effect was first introduced by Albert Einstein in 1905.The idea of ​​the photovoltaic effect was introduced in 1839 by AE Becquerel, a French physician.
Kinetic energyDuring the photoelectric effect, the kinetic energy of the emitted electrons is very important.Kinetic energy is not important during the photovoltaic effect.
Electron releaseThe photoelectric effect releases an electron into open space after the incidence of light.As a consequence of the incident light, the photovoltaic effect causes the movement of electrons in different materials.
ApplicationsThis effect is used in imaging technology, the study of nuclear processes, and to give theoretical information about the transition of electrons between different energy states in atoms, etc.Solar cells work on the concept of photovoltaic effect.
PerformanceIt can be observed in a cathode ray tube with the participation of an anode and a cathode attached to an external circuit.This effect takes place between two different metals that combine with each other in a solution.
Electric current generationSuch an effect does not generate electric current.Electric current is produced in this effect.
Binding potentialThere is no junction potential in the photoelectric effect.In this effect, the emitted electrons push through the binding potential.
Energy requiredIt occurs when photons provide enough energy to exceed the electron binding energy.This effect occurs when the photons provide enough energy to cross the potential excitation barrier.

Photoelectric effect vs. photovoltaic effect

The photoelectric effect is the process that takes place 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 introduce 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 physician. 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 the 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, whereas; 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 the 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 potential excitation 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 displacement of electrons between different energy states in atoms. On the other hand, solar cells work on the concept of 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 the interaction of light 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, the electrons in the substance absorb energy and release it into free space as they exit 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 energy provided is equal to the work function only, it will make the emitted electrons stay on the surface of the metal. They will not be able to move due to the absence of kinetic energy.

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

Also, if the metal is placed in a vacuum tube as a cathode with a receiving node on the other side along with an external circuit, the electrons emitted from the cathode will be attracted to the anode, which is held at a positive voltage. So a current is transmitted into the vacuum and completes the circuit. This discovery by 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.

The photoelectric effect is the expulsion or emission of electrons from the atoms of a metal when a light ( electromagnetic radiation ) hits the metal , freeing them from the attraction of their atom.

Materials that emit electrons when absorbing electromagnetic radiation from light are called ” photoemitters ” and are all metals.

If we remember that electric current is simply a movement of electrons, the photoelectric effect can be a way of generating electric current, since light moves electrons, but we will see that later.

In fact the word photoelectric comes from Photo = Light and from the adjective “electric”.

Actually the particles that release electrons are photons .

Photons are massless but energetic particles that are part of light.

In reality, light is made up of an infinity of very small particles, without mass but with energy, called “photons”.

When these photons reach the metal by means of light, by striking an electron of the metal atom, if the photon has enough energy, this energy gives it to the electron and frees it from its last layer, that is, it frees it from the attraction of the atom, being free by the metal or expelling it out of it.

Electrons closest to the nucleus are tightly bound and have little energy.

The outermost ones are the ones with the most energy, but the ones that are easiest to make them leave the atom because they are precisely the furthest away and least attached to the nucleus.

These electrons are the ones that eject or release the photons upon reaching the metal and are called ” valence electrons ” because they are the ones that can form bonds with other nearby atoms.

Actually, the valence electrons of an atom of metal are always linked to other electrons of another nearby atom of the metal through what is known as a covalent bond. If a photon ejects an electron from an atom, it also breaks that covalent bond it had, leaving a hole in the bond. . This is what is known as an electron-hole pair. Whenever an electron is released, a hole is left in the atom.

Applications of the Photoelectric Effect

Besides photovoltaic already explained, the photoelectric effect is used in a large number of devices, including photocopiers, light meters, and even electronic components as photodiodes, phototransistors, optocouplers ,.

The other great application for the photoelectric effect is scintillators or radiation detectors.

A scintillator is a device that will emit light when it detects radiation from a light source in the laboratory or from a cosmic (space) source.

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 electrical current and voltage in the material. This current is known as a photocurrent. The idea for this effect was put forward in 1839 by a French physician named AE Becquerel. He came across this concept when he was trying to generate a current between two plates of gold and platinum.

When he dipped the gold and platinum into a solution and exposed them to light, the electrons in the metal’s border strip absorbed the energy from the light 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 go 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.

One of the main applications of the photoelectric effect is the photovoltaic effect, in fact, many times people speak of one or the other as if they were the same, but they really are not.

We can say that the photovoltaic effect is a process of the photoelectric effect, it is when thanks to the photoelectric effect we manage to generate electric current, for example in a solar cell or in solar panels.

The photoelectric effect produces free electrons (charges) and the photovoltaic effect produces electric current thanks to those free electrons released through the photoelectric effect or process.

The elements to produce the photovoltaic effect are the solar panels or cells that are P and N semiconductors joined (PN junction ).

Conclution

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.

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