Heat generation of phosphor layer in white LED

In summary, the package of a phosphor converted white LED contains two heat generation mechanisms - Joule heating at the junction temperature of the blue LED and heat generation of the yellow phosphor layer due to stokes shift and blue light absorption. The hottest part in the LED package can be either the junction or the phosphor layer. If the junction temperature is 100°C and the temperature of the phosphor layer is 30°C, then the measured temperature of the phosphor layer surface would be 130°C. This indicates that thermal accumulation may be a valid phenomenon in the system. Further expertise may be needed to fully understand the behavior of the LED phosphor layer.
  • #1
compound
5
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In a package of a phosphor converted white LED (blue LED + Yellow phosphor), two heat generation mechanisms exist.
1. Joule heating at junction temperature of blue LED
2. Heat generation of the yellow phosphor layer due to stokes shift and blue light absorption.

Now I have questions.
1. Where is the hottest part in the LED package? junction or phosphor layer?

2. If
junction temperature = 100°C
generated temperature of phosphor layer = 30°C

then if i measure the temperature of the phosphor layer surface, what is the temperature? 130°C ?
(on the other words, thermal accumulation phenomenon is valid in the system?)

LED.PNG


is their anybody expert for LED phosphor layer?
 
  • #3
I've wondered about this as well. I know that leds in the 5w range or above need rather large heat sinks or they self destruct. This alway surprised me for such small wattage ranges. I suspect a thermal run-away happens like what used to happen in early transistors.
 

Related to Heat generation of phosphor layer in white LED

What is the phosphor layer in a white LED?

The phosphor layer is a thin coating of phosphor material applied to the blue LED chip in white LEDs. This layer is responsible for converting the blue light emitted by the chip into white light.

How does the phosphor layer generate heat in a white LED?

The phosphor layer absorbs some of the blue light from the LED chip, which causes it to heat up. This heat is then transferred to the surrounding components, including the LED chip itself, resulting in an overall increase in temperature.

What factors can affect the heat generation of the phosphor layer?

Several factors can impact the heat generation of the phosphor layer, including the intensity of the blue light, the thickness and composition of the phosphor layer, and the ambient temperature. Additionally, the efficiency of the LED chip can also play a role in heat generation.

How does heat affect the performance of a white LED with a phosphor layer?

Excessive heat can decrease the efficiency and lifespan of a white LED with a phosphor layer. This is because high temperatures can cause the phosphor material to degrade, leading to a decrease in light output and color accuracy.

What measures can be taken to reduce heat generation in white LEDs with a phosphor layer?

One way to reduce heat generation in white LEDs is to improve the efficiency of the LED chip, which will result in less energy being converted into heat. Another option is to optimize the composition and thickness of the phosphor layer to minimize light absorption and heat generation. Additionally, implementing proper heat dissipation techniques, such as heat sinks and thermal management materials, can also help to reduce heat buildup in white LEDs with a phosphor layer.

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