AS01b-21 QRLEDs for the LCD backlights

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January 19, 2022 4:14 pm

Good afternoon.

A very beautiful and vibrant poster. I had one question, what is the purpose of “place the injected LED under UV light to crystallize”?


YUEN, Ching Ho Edward
January 19, 2022 4:16 pm
Reply to  KHURANA, Param

Thank you for your comment. The UV light crystalizes the liquid solution on the LED and turns them into solid form, which is hard to destroy, and the position of the liquid would not change over movement.

YEUNG, Chun Kit
January 19, 2022 4:50 pm
Reply to  KHURANA, Param

Nice question! As mentioned in Figure 3, we have to cover the LED chips with 3 layers. Originally, those layers are liquid-form NOA61 and QR solution. They are photopolymers that can be crystallized by UV light. If we don’t do this, those liquids will mix together and the protective purpose of the NOA61 to the QR materials will be gone.
Honestly, the crystallization progress is called polymerization.

PUROHIT, Anushka
January 19, 2022 4:03 pm

Super cool! Would love for you to take a look at my poster as well – “Winko Box”!

YEUNG, Chun Kit
January 19, 2022 4:16 pm

Sure~Let’s go!

YUEN, Ching Ho Edward
January 19, 2022 4:17 pm

You are welcome, thank you! We will have a look now.

YAN, Kai Hang
January 19, 2022 3:02 pm

Good afternoon. I have some question on the structure of QRLED chip.

From your poster, it contains 3 layers with different materials. But it seems there are not much detail on why this material was choosed and why it has such property of satisfy the requirement.
Can you explain more on the structure and details of those materials?

Btw, nice RGB section background color 🙂

Last edited 2 years ago by YAN, Kai Hang
NG, Wing Hong
January 19, 2022 3:13 pm
Reply to  YAN, Kai Hang

Thanks for your comment, we assume you are referring Figure 3, the small box describing the structure of a QRLED chip. As you can see there are 3 kinds of materials, including
Blue LED chip (a tiny hardware that emits blue light);
QR material (major color Quantum Rods solution);
NOA61 solution (transparent protective solution);

The usage of the blue LED chip is simple, it is the basic component to emit light as an LED. Yet only emitting light from an LED is not enough, the quality and efficiency are not good, so we have to inject QR materials to the LED chips to increase the quality of the light, and this is what our project does, QRLED. However, QR materials can be easily burnt by the energy or light emitted by the LED ship, which causes decrease in the quality, so we add a protection layer, NOA61 solution, to prevent the destruction of the QR materials and the LED chip. So, you can see different layers described in Figure 4, which LED, protection layer, color QR layer are arranged alternatively to keep the stability and efficiency at the same time.

YAN, Kai Hang
January 19, 2022 3:28 pm
Reply to  NG, Wing Hong

Thanks for the additional information

YEUNG, Chun Kit
January 19, 2022 3:23 pm
Reply to  YAN, Kai Hang

Thank you! We are using NOA61 photopolymer as the protective layers on the top and bottom of the chips. We use NOA61 because it provides a good water vapor transmission rate(WVTR) and oxygen transmission rate(OTR) after we polymerized the NOA61. With a lower rate, the LED chips are more stable for long usage as the water vapor and oxygen are less easier to deal negative impact to the chips and the QR materials.
Besides, it is transparent and cheap too.

YAN, Kai Hang
January 19, 2022 3:27 pm

Thanks for the additional details of NOA61 photopolymer

QUADEER, Ahmed Abdul
January 19, 2022 2:43 pm

Interesting project and nice poster. You mention this statement in the evaluation: “Our goal is to maintain the same level for the 3 curves, with smooth slope that looks like Gaussian curve.” Can you explain how doing this will help to achieve you project objective?

NG, Wing Hong
January 19, 2022 3:01 pm

Thanks for your comment. Our goal is to produce a high stability and high efficiency QRLED in white color, this is because white color light is formed by Red, Green and Blue light, so we can evaluate three main color in a single LED.

In figure 5, we consider the wavelength/response graph as a key information to judge the efficiency of our QRLED. With the information from the graph, you can see there are 3 color curves representing RED, GREEN and BLUE color. Maintaining a same level (response level) means equal “quantity” of light is emitted from the LED, which can produce perfect white light. If one of the color light, say blue, is dominating the response level, the output will be more “blue” but not white, which induce a huge influence to the color quality.

For the shape of the slope, keeping a smooth slope means fewer noises are included in the LED. As you can see at the bottom part of the figure, where response level lies between 0-0.1, there are some fluctuation at the 3 curves, it shows some noise in that wavelength, which is something that we don’t want (it affects the quality of the LED). So, keeping a smooth slope here can remove all noises in the light.

Therefore, if we can observe a “perfect” curve for each color, it will be a strong evidence to prove our QRLED is performing good in efficiency.

FAN, Zhiyong
January 19, 2022 2:24 pm

There are grammar errors in the poster

NG, Wing Hong
January 19, 2022 2:28 pm
Reply to  FAN, Zhiyong

Thanks for your comment, we will check the content again to correct all the grammar errors.