VS - Lighting Systems - Lighting - 998542

Electrons and holes combine in the border zone between the P and N regions (called depletion zone) and release energy called photons. This is the basis of light emission in LEDs.

The LED chip is assembled into a package for mechanical protection, optical light diffusion, electrical connection, and thermal interface to dissipate heat. To improve the overall efficiency of LED packages it is important to optimize both light output and heat extractions. Light Emitting Diode technology has dramatically improved in the past decade. Until recent times the use of LED in automotive lighting was limited to rear signalling purposes due to limited light output and heat dissipation issues.

l Photons released from the LED generate light.

l Photons not released from the LED generate heat.

n-Crystal

p-Crystal

-

+

Depletion zone

Electrons

Holes

LEDs internal recombinations

The ratio between released photons to absorbed photons in the LED structure determines the light source efficiency.

Radiative recombinations generate light

Light extraction

Leds light and heat extraction

Active layer (depletion zone)

Heat extraction

Non-radiative recombinations generate heat

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