Why do light-emitting diodes come in different colors?

Release Date:

2021-02-25

　　LED stands for Light-emitting diode It is a solid-state semiconductor device that can directly convert electrical energy into light. Light-emitting diodes are made from group III–IV compound semiconductors, such as GaAs (gallium arsenide), GaP (gallium phosphide), and GaAsP (gallium phosphorus arsenide), with a PN junction at their core. Consequently, they exhibit the typical I–V characteristics of a P–N junction: forward conduction, reverse cutoff, and breakdown behavior. The heart of an LED is a semiconductor chip, one end of which is mounted on a support bracket; one terminal serves as the negative electrode, while the other is connected to the positive terminal of the power supply, after which the entire chip is encapsulated in epoxy resin.

 

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　　The English abbreviation for light-emitting diode is LED. In everyday life, you can see it in various colors. Light-emitting diode Some emit green light, some red, and others blue—each with a dazzling brilliance—while still others produce invisible infrared and ultraviolet radiation. So what determines the color of a light-emitting diode? When an electron transitions from the conduction band to the valence band, it emits a photon whose energy E is equal to the bandgap energy Eg. The wavelength λ of the emitted photon is given by λ = 1.24/Eg (in micrometers). Thus, the bandgap of the semiconductor essentially dictates the color of the light emitted by the diode.

　　A full-color LED display typically consists of numerous RGB tricolor units. Light-emitting diode It is composed of pixel units, each containing RGB LEDs; by controlling the on/off states of these pixel groups, full-color images in various hues can be displayed. Currently, outdoor shopping malls remain the primary market for LED displays, accounting for 60% of the industry’s share, and in the future, such displays are bound to become ubiquitous on streets and in neighborhoods alike.

More information

What is a light-emitting diode?

Light-emitting diodes are commonly referred to as LED beads. They are used in a wide range of applications and can be seen on streets and in alleys everywhere. For example, traffic lights at intersections remind people to obey traffic rules; remote controls transmit or receive signals; they can be used to display images on ultra-large screens; and various streetlights provide warm illumination at night. Even everyday household appliances rely on their contributions.

What are the tips for selecting LED chips?

1. Brightness: LED brightness varies, and so does the price. LEDs used in LED lighting must comply with laser safety classification standards.

What factors influence the price differences of LED light beads?

LED chips are a well-known product in the LED industry; however, many people are less familiar with their pricing. What causes such wide variations in LED chip prices? Below, we will outline the factors that influence LED chip prices.

What is the light-emitting principle of LED chips?

An LED chip is a light-emitting diode, and an LED bulb is simply the common, colloquial term for an LED.

Are you familiar with full-color LED chip-on-board modules for side mounting?

The brightness of full-color LED surface-mount devices is closely related to the LED’s viewing angle. The narrower the viewing angle, the higher the brightness; moreover, differences in manufacturing processes can lead to significant variations in service life. For a 5-mm LED with a 180-degree viewing angle, the white-light luminous intensity is only a few hundred mcd, whereas for a 15-degree viewing-angle LED, the luminous intensity exceeds 10,000 mcd. When high-power LEDs are used outdoors, the brightness is even greater. Single-power LEDs include 1 W, 3 W, and 5 W models; some high-power LEDs can be combined to form a single high-power LED with output up to several hundred watts. Color temperature is independent of brightness, but brightness is directly related to the lumen value.

Key Considerations for Full-Color SMD LEDs on the Side

Side-view full-color LED chips, also known as surface-mount LEDs, are a type of simple lighting device. Their light-emitting principle is based on passing an electric current through a compound semiconductor; when electrons and holes recombine, the excess energy is released in the form of light, thereby producing illumination.