The principle of light emitting diode the more complete the answer, the better .

Fifty years ago, the basics of how semiconductor materials can produce light were understood, and the first commercial diode was created in 1960. LED is the abbreviation of Light Emitting Diode (Light Emitting Diode) in English.

Its basic structure is a piece of electroluminescent semiconductor material, placed on a shelf with leads, and then sealed with epoxy resin around to protect the internal core, so the LED has good seismic performance. The core part of a light-emitting diode is a wafer composed of p-type semiconductors and n-type semiconductors, and there is a transition layer between the p-type semiconductor and the n-type semiconductor, called the p-n junction. In the PN junction of some semiconductor materials, when the injected minority carriers are recombined with the majority carriers, the excess energy is released in the form of light, thus directly converting electrical energy into light energy.

The PN junction is added with a reverse voltage, and a few carriers are difficult to inject, so they do not emit light. This kind of diode made by using the principle of injection electroluminescence is called light-emitting diode, commonly known as LED. When it is in the forward working state (that is, the two ends add the forward voltage), when the current flows from the LED anode to the cathode, the semiconductor crystal emits light of different colors from ultraviolet to infrared, and the intensity of the light is related to the current.

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The gas ionizes, and the electron transitions emit light.

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Light-emitting diodes are abbreviated as LEDs. It is a device with two electrodes among electronic components that allows only a single direction of current to flow. It is made of compounds containing gallium (Ga), arsenic (As), phosphorus (P), nitrogen (N), etc.

Light-emitting diode is one of the most commonly used electronic components, its biggest feature is unidirectional conduction, that is, the current can only flow from one direction of the diode, the role of light-emitting diode has rectifier circuits, detection circuits, voltage stabilization circuits, modulation of various circuits.

The crystal diode is a p-n junction formed by a p-type semiconductor and an n-type semiconductor, which forms a space charge layer on both sides of its interface and has a self-built electric field. In the absence of an applied voltage, the diffusion current caused by the difference in carrier concentration on both sides of the PN junction and the drift current caused by the self-generated electric field are equal. When there is a forward voltage bias in the external area, the mutual suppression effect of the external electric field and the self-built electric field increases the diffusion current of the carriers and causes the forward current.

When there is a reverse voltage bias in the outside world, the external electric field and the self-built electric field are further strengthened to form a reverse saturation current i0 that is independent of the reverse bias voltage value within a certain reverse voltage range. When the applied reverse voltage is high to a certain extent, the electric field strength in the charge layer of the pn junction space reaches a critical value, resulting in the multiplication process of carriers, generating a large number of electron-hole pairs, and producing a large reverse breakdown current, which is called the breakdown phenomenon of the diode. The reverse breakdown of the PN junction is divided into Zener breakdown and avalanche breakdown.

Light-emitting diodes are referred to as LEDs and have the following characteristics:

1. Safety voltage.

LED uses a low-voltage power supply, and the power supply voltage is between DC 3-24V, which is a safer power supply than using a high-voltage power supply, especially suitable for public places.

2. Energy-saving model.

The energy consumption is about 80% less than that of incandescent lamps with the same light efficiency, and about 40% less than that of energy-saving lamps.

3. The applicability is strong.

It is small in size, can be prepared into a variety of shapes, and is suitable for volatile environments.

4. Fast response time.

Its incandescent lamps have a response time in the millisecond range, and LED lamps have a response time in the nanosecond range.

5. There are many colors.

Light-emitting diodes have red, yellow, green, blue, and orange multi-color light emitting. The working voltage of the red fluorescent tube is small, and the working voltage of the red, orange, yellow, green, and blue LEDs of different colors increases sequentially.

6. **Low.

LED is becoming more and more popular, and due to the power-saving characteristics of LED, the places used will gradually increase.

Diodes are one of the most common devices in semiconductor devices, and most semiconductors are mostly made of mixed semiconductor materials (atoms and other substances) The LED conductor material is usually aluminium arsenide, in pure aluminium arsenide, all atoms are perfectly bonded to their neighbors, leaving no free electron connection to the defeated current.

Photo-emitting diodes, such as those used in digital display clocks, determine the frequency of the photons, in other words, the color of the light. When all diodes emit light, most are not very efficient. In ordinary diodes, the semiconductor material itself attracts a large amount of light energy.

A light-emitting diode is covered by a plastic bulb that concentrates light in a specific direction.

LED (Light Emitting Diode) is a solid-state semiconductor device that can directly convert electricity into light. The heart of an LED is a semiconductor wafer with one end attached to a bracket, one end is the negative electrode, and the other end is connected to the positive electrode of the power supply, so that the entire wafer is encapsulated by epoxy resin. A semiconductor wafer is made up of two parts, one is a p-type semiconductor, in which holes dominate, and the other end is an n-type semiconductor, which is mainly electrons here.

But when these two semiconductors are connected, a "p-n junction" is formed between them. When an electric current is applied to the wafer through the wire, the electrons will be pushed to the p-region, where the electrons will recombine with the holes, and then the energy will be emitted in the form of photons, which is the principle of LED luminescence. The wavelength of the light determines the color of the light and is determined by the material that forms the p-n junction.

The relationship between the spectrum of visible light and the white light of LEDs. As we all know, the wavelength range of the visible light spectrum is 380nm to 760nm, and it is the seven colors of light that can be perceived by the human eye - red, orange, yellow, green, cyan, blue, and violet, but each of these seven colors of light is a monochromatic light. For example, the peak wavelength of red light emitted by LEDs is 565nm.

There is no white light in the spectrum of visible light, because white light is not monochromatic light, but composite light composed of a variety of monochromatic light, just as sunlight is white light synthesized from seven monochromatic lights, and white light in color television is also synthesized by the three primary colors red, green, and blue. It follows that for an LED to emit white light, its spectral characteristics should include the entire visible spectral range. But to manufacture LEDs with this performance, it is not possible under the current process conditions.

According to people's research on visible light, the white light that can be seen by the human eye requires at least a mixture of two kinds of light, that is, two-wavelength luminescence (blue light + yellow light) or three-wavelength luminescence (blue light + green light + red light). The above two modes of white light require blue light, so the ingestion of blue light has become a key technology for the manufacture of white light, that is, the "blue light technology" pursued by major LED manufacturing companies. At present, there are only a few manufacturers in the world who have mastered the "blue light technology", so the promotion and application of white LEDs, especially the promotion of high-brightness white LEDs in China, there is still a process.

What are the characteristics of light-emitting diodes?

LED light emitting principle: LEDs are made of - group compounds, such as GAAS (gallium arsenide), GAP (gallium phosphide), GAASP (gallium arsenide phosphorus) and other semiconductors, and its core is PN junction. Therefore, it has the I-N characteristics of the general p-n junction, that is, forward conduction, reverse cut-off, and breakdown characteristics.

In addition, under certain conditions, it also has luminescent properties. At forward voltage, electrons are injected into the p-region by the n-region, and holes are injected into the n-region by the p-region. A portion of the minority carriers (few) that enter the opposing region reunites with the majority (manyon) and emits light.

Since the light-emitting diode has the limitation of the maximum forward current IFM and the maximum reverse voltage VRM, it should be guaranteed that this value should not be exceeded when used.

A simple explanation of light-emitting diodes (LEDs). , LED lights are how to accommodate.

The operating voltage is very low (some are only a few volts); The working current is very small (some can emit light only a few tenths of a milliampere); Good impact and seismic resistance, high reliability and long life; The intensity of the luminous light can be easily modulated by modulating the strength of the passing current.

Because of these characteristics, light-emitting diodes are used as light sources in some optoelectronic control devices and as signal displays in many electronic devices. The core of the tube is made into strips, and 7 strips of light-emitting tubes are used to form a 7-segment semiconductor digital tube, each of which can display 0 9, 10 Arabic numerals and some letters such as a, b, c, d, e, f (must be case-sensitive).

Light-emitting diodes (LEDs) have unidirectional conductivity, and some high-power LEDs can be used for lighting. High light conversion rate, long life, average 100,000 hours. Low starting voltage, good stability, etc.

The photoelectric conversion efficiency is high, and most of the electrical energy is converted into light energy, and there is only a small amount of heat.