Working principle and detection method of LED light-emitting diode

LED (Light Emitting Diode) is a common semiconductor device widely used in fields such as indicator lights, display screens, lighting, and communication.



1. Working principle of LED

LED is an electronic device that operates based on the photoelectron effect generated by semiconductor materials when injecting charge carriers. The following is a brief overview of the working principle of LED:

PN junction: LED is a PN structure composed of N-type and P-type semiconductors. When a forward voltage is applied to the PN junction, electrons diffuse from the N region to the P region, while holes diffuse from the P region to the N region.

Carrier recombination: When electrons and holes meet, they recombine and release energy, which is converted into photons. This process is called radiative recombination.

Luminescence: Photons propagate within a crystal and release visible light near the PN junction. According to the different semiconductor materials, LEDs can emit light of different colors.

Material selection: Choosing different semiconductor materials can achieve different wavelengths of luminescence, for example, gallium nitride (GaN) can achieve blue light LED.

2. LED detection methods

The performance evaluation and quality control of LED require accurate and reliable detection methods. The following are several common LED detection methods:

1. Appearance inspection: It is the simplest and most intuitive LED inspection method. The quality of LED can be judged by visually observing whether the surface of the LED is flat and whether the color is uniform.

2. Optoelectronic parameter testing: Use optoelectronic parameter testing instruments, such as light intensity meters and color temperature meters, to measure the brightness, color temperature, color coordinates, and other parameters of LED to ensure that the optical performance of LED meets the requirements.

3. Electrical performance testing: Use a multimeter or a specific LED testing instrument to test the electrical performance parameters of the LED, such as current, voltage, and power, to ensure that the LED is within its normal operating range.

4. Thermal coupling test: The luminous efficiency of LED is affected by temperature, so conducting thermal coupling test, that is, testing the photoelectric parameters of LED at different temperatures, can help evaluate the performance stability of LED in different environments.

5. Lifetime testing: Conduct lifespan testing on LEDs to simulate the working conditions that may be encountered during long-term use, in order to determine the lifespan and stability of LEDs.

6. Wavelength testing: Use a spectral analyzer or wavelength testing instrument to measure the wavelength of the light emitted by the LED to ensure color accuracy and consistency.

LED, as an efficient and environmentally friendly lighting and display technology, has been widely used in various fields. Understanding the working principle and effective detection methods of LED helps to ensure the quality and performance of LED products, playing an important role in engineering design and manufacturing processes.