Absolute Efficiency:
Absolute efficiency refers to the overall efficiency of an LED in converting electrical energy into visible light. It is calculated by dividing the total luminous flux (measured in lumens) emitted by the LED by the total electrical power (measured in watts) consumed by the LED. The absolute efficiency is commonly expressed as a percentage.
For example, if an LED emits 100 lumens of light while consuming 10 watts of electrical power, its absolute efficiency would be:
Absolute Efficiency = (100 lumens / 10 watts) * 100 = 10%
In this case, the LED converts 10% of the electrical energy it consumes into visible light, while the remaining 90% is lost as heat or other forms of energy.
Relative Efficiency:
Relative efficiency, on the other hand, compares the performance of an LED to a reference light source, usually an incandescent light bulb. It is calculated by dividing the luminous flux of the LED by the luminous flux of an incandescent light bulb that consumes the same amount of electrical power. The relative efficiency is expressed as a percentage or a ratio (e.g., LED efficiency / Incandescent efficiency).
For example, if an LED emits 100 lumens of light while consuming 10 watts of electrical power, and an incandescent light bulb emits 10 lumens of light while consuming the same 10 watts, the relative efficiency of the LED would be:
Relative Efficiency = (100 lumens / 10 lumens) = 10
In this case, the LED is 10 times more efficient than the incandescent light bulb in converting electrical energy into visible light.
Which Efficiency Metric to Use:
The choice of which efficiency metric to use depends on the context and purpose of the discussion. Absolute efficiency provides a measure of the overall conversion efficiency of an LED, while relative efficiency helps to compare the performance of different light sources.
In general, absolute efficiency is a more useful metric when evaluating the overall performance and energy efficiency of an LED. However, relative efficiency can be helpful when comparing the lighting output of different technologies or when making decisions about lighting upgrades or replacements.
Blue LEDs Efficiency:
Blue LEDs have historically lagged behind other LED colors in terms of efficiency. This is primarily due to the higher energy required to produce blue light compared to other colors. However, advancements in semiconductor materials and device design have significantly improved the efficiency of blue LEDs in recent years.
While the absolute efficiencies of blue LEDs are still lower compared to other colors, they have reached impressive levels. State-of-the-art blue LEDs can achieve absolute efficiencies of around 60-80%, meaning they convert a significant portion of the electrical energy they consume into blue light.
In terms of relative efficiency, blue LEDs still have some catching up to do compared to other colors. However, they have made substantial improvements and now outperform incandescent light bulbs by several orders of magnitude.
Overall, blue LEDs have come a long way in terms of efficiency, and they continue to improve as technology advances.
