Forward current (If) refers to the amount of current flowing through an LED when operating in forward bias, also known as drive current. A light-emitting diode has a p-n junction (positive-negative junction) sandwiched between oppositely doped layers. When electrical potential (voltage) is applied to the p-n junction current flows from the p-side, or anode, to the n-side, or cathode. Electrons and holes flow into the active region where they recombine to generate photons (bundles of light energy).
The current fed to an LED determines the amount of luminous flux generated in the LED package. Increasing the drive current can maximize the light emitted from the chip. However, the high quantum efficiency of the widely used InGaN-based LEDs has only been achieved at relatively low current densities. Operating an LED beyond its saturated current density will cause its efficiency to be reduced. This phenomenon is known as efficiency droop or current density droop. At higher current density operation, a non-radiative carrier recombination process called Auger recombination dominates. Auger recombination generates heat instead of light. The atomic defect generation and growth in the active region of an LED can be accelerated at higher temperatures due to overdriving, which leads to premature lumen degradation and color shift. As such, the drive current must be properly controlled to avoid efficiency droop.
The current fed to an LED determines the amount of luminous flux generated in the LED package. Increasing the drive current can maximize the light emitted from the chip. However, the high quantum efficiency of the widely used InGaN-based LEDs has only been achieved at relatively low current densities. Operating an LED beyond its saturated current density will cause its efficiency to be reduced. This phenomenon is known as efficiency droop or current density droop. At higher current density operation, a non-radiative carrier recombination process called Auger recombination dominates. Auger recombination generates heat instead of light. The atomic defect generation and growth in the active region of an LED can be accelerated at higher temperatures due to overdriving, which leads to premature lumen degradation and color shift. As such, the drive current must be properly controlled to avoid efficiency droop.
