What is the Difference Between Photoluminescence and Electroluminescence

The key difference between photoluminescence and electroluminescence is that photoluminescence occurs following the absorption of a photon, whereas electroluminescence occurs through the generation of light by the application of an alternating current to a semiconductor.

Photoluminescence and electroluminescence are two types of luminescence. Luminescence is the emission of light by a substance that has not been heated. In contrast, luminescence types such as fluorescence and phosphorescence occur from heated bodies.

CONTENTS

1. Overview and Key Difference
2. What is Photoluminescence  
3. What is Electroluminescence
4. Photoluminescence vs Electroluminescence in Tabular Form
5. Summary – Photoluminescence vs Electroluminescence 

What is Photoluminescence?

Photoluminescence is a form of luminescence that occurs with a photoexcitation via photon absorption. This light emission occurs when a substance absorbs electromagnetic radiation and re-emits the radiation. This process initiates with photoexcitation. This means the electrons of the substance undergo excitations when the substance absorbs photons, and electrons move to higher energy states from lower energy states. Following these excitations, there are relaxation processes as well. In the relaxation step, photons are re-radiated or emitted. The time period between the absorption and emission of photons may vary depending on the substance.

There are several forms of photoluminescence that differ from each other according to several parameters. When considering the wavelength of absorbed and emitted wavelengths of photons, there are two major types as fluorescence and resonance fluorescence. In fluorescence, the wavelength of emitted radiation is lower than the wavelength of absorbed wavelength. In resonance fluorescence, the absorbed and emitted radiation have equivalent wavelengths.

What is Electroluminescence?

Electroluminescence is a chemical phenomenon in which a material emits light as a response to the passage of an electric current. We can abbreviate it as EL. This is both an optical phenomenon and an electrical phenomenon. It can occur in the presence of an electric current or in the presence of a strong electric field. This feature is distinct from black body light emission that results from one of the following causes: heat, a chemical reaction, sound, and other mechanical action.

When considering the mechanism of electroluminescence, it occurs as a result of radiative recombination of electrons and holes in a material such as a semiconductor. In this process, the excited electrons tend to release their energy in the form of photons. We can separate the electrons and holes prior to the recombination process by doping the semiconductor in order to form a p-n junction or through the excitation by the impact of high-energy electrons that are accelerated by a strong electric field.

What is the Difference Between Photoluminescence and Electroluminescence?

Luminescence is the emission of light by a substance that has not been heated. Photoluminescence and electroluminescence are two types of luminescence. The key difference between photoluminescence and electroluminescence is that photoluminescence occurs following the absorption of a photon, whereas electroluminescence occurs through the generation of light by the application of an alternating current to a semiconductor.

The following figure summarizes the difference between photoluminescence and electroluminescence in tabular form for side by side comparison.

Summary – Photoluminescence vs Electroluminescence

Luminescence is the emission of light by a substance that has not been heated. Photoluminescence and electroluminescence are two types of luminescence. The key difference between photoluminescence and electroluminescence is that photoluminescence occurs following the absorption of a photon, whereas electroluminescence occurs through the generation of light by the application of an alternating current to a semiconductor.

Reference:

1. “Photoluminescence.” An Overview | ScienceDirect Topics.

Image Courtesy:

1. “Fluorescence rainbow” By Maxim Bilovitskiy – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “Electroluminescent panel spectrum” (CC BY-SA 3.0) via Commons Wikimedia