Calculators » Optical and Photonic » LED Power Output Calculator: Internal Quantum Efficiency Explained

LED Power Output Calculator: Internal Quantum Efficiency Explained

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This document explains how to calculate LED power output based on its internal quantum efficiency and other factors. It provides the relevant equation and a calculator for determining power output.

Definition of Internal Quantum Efficiency

The internal quantum efficiency (η) of an LED represents the proportion of electrons injected into the depletion layer that successfully generate photons.

In simpler terms, if ‘N’ electrons are injected into the depletion layer every second, the device’s power output (P) can be expressed as:

P = η * N * h * v = η * I * h * v / e

Where:

  • I is the forward current.
  • e is the electronic charge.
  • h is Planck’s constant.
  • v is the frequency of the emitted light.

This equation is derived as follows:

LED Power Output Calculator

Inputs

Outputs

Use the calculator to determine LED power output based on internal quantum efficiency:

Example:

  • LED radiation (λ): 900 nm
  • LED forward current: 20 mA
  • Internal Quantum Efficiency (η): 2 %

Output:

  • LED Power Output: 0.55 mWatt

LED Internal Quantum Efficiency Equation | LED Power Output Formula

The following equation links LED internal quantum efficiency to power output and is used in the calculator:

LED Internal Quantum Efficiency and Power Output Equation