Why OLED & not RGB LEDs?

[Edward78]

OLEDs burn in & the layers that make the colors die. Why don't they just use RGB LEDs? They can just make the color with out the layer to do it.

[Levent]

Arent they essentially the same thing?

[Edward78]

Just now, Levent said:

Arent they essentially the same thing?

Why do oleds need that layer to make the colors if those LEDs can make colors?

[podkall]

one google search:

 

apparently LED = LCD for google

 

[manikyath]

16 minutes ago, Edward78 said:

Why do oleds need that layer to make the colors if those LEDs can make colors?

it's essentially the same thing, but made in a way that is feasible to manufacture a display consisting of a million of them.

 

let's say an RGB LED at scale is half a cent... that's still 10k usd worth of LEDs.

[Electronics Wizardy]

I'm pretty sure its a size thing. Look up microled, its basically what you want. I'm pretty sure they haven't come up with a way to 'print' led like they can with oled displays currently.

 

You can get LED displays like this, but there very low pixel density and used for things like billboards.

 

2 minutes ago, podkall said:

one google search:

 

LED display are a bad way of saying led backlight lcd displays, and basically behave like the older CCFL backlight displays. A microled display would be much more like a oled with perfect blacks.

 

 

[Kilrah]

24 minutes ago, Edward78 said:

Why don't they just use RGB LEDs?

That's MicroLED displays. Way too expensive for us at this point. 

[GuiltySpark_]

1 hour ago, Kilrah said:

That's MicroLED displays. Way too expensive for us at this point. 

This.

 

What you're asking for exists, its just going to be a while before the pricepoint is where OLED's are now. 

[saintlouisbagels]

4 hours ago, Edward78 said:

OLEDs burn in & the layers that make the colors die. Why don't they just use RGB LEDs? They can just make the color with out the layer to do it.

This is exactly what MicroLED is and it's incredibly, prohibitively expensive and requires a lot of cooling.

Linus' saga of considering the Samsung The Wall would've requires tens of thousands of $$ in just room cooling.

[Alex Atkin UK]

18 hours ago, Edward78 said:

OLEDs burn in & the layers that make the colors die. Why don't they just use RGB LEDs? They can just make the color with out the layer to do it.

15 hours ago, GuiltySpark_ said:

This.

 

What you're asking for exists, its just going to be a while before the pricepoint is where OLED's are now. 

 

Plus its probably still going to need a transmission layer, as its more efficient to have blue LEDs and then convert the colour with quantum dots.  If you make an LED natively emit different colours, its a less pure colour and different colours emit different amounts of light and wear out at different rates.

 

Because yes, LEDs "burn in" too, its just a matter of how quickly.   You don't typically notice with an LED backlight as the whole array wear out at the same rate, so the screen just gets duller over time.  Now local dimming is more common, we may start to see an issue where certain sections of the screen are duller than others, if those sections were constantly displaying something much brighter than the rest of the screen.  This may be offset with the same tech they use for OLED, run those LEDs harder to get the brightness back up, or dim the rest of the screen to match.  Either way, these are hacks to get around the inevitable wearing out of LEDs of any kind.

So for microLED you also need to make them more efficient so they do not burn out from getting too hot.  There's a lot of research going into making better lenses to go on top of LED/OLEDs in order to get more of the lights into our eyeballs, so they can be run at lower power levels.

[Stahlmann]

MicroLED is basically exactly that. Small LEDs. But they're still insanely expensive, not to mention the pixels (LEDs) still can't get nearly small enough to get to the pixel density you'd need for 32" 4K for example.

[Glenwing]

Using conventional LED structures as the pixel elements themselves isn't practical, as they can't just be blindly miniaturized to the level that's needed for the pixel densities a display needs. Some new type of LED designs are needed in order to achieve this. Creation of such "micro LEDs", as mentioned above, is an ongoing challenge which is still in development.

 

As an example, here is a snippet from a recent paper:

https://www.mdpi.com/2073-4352/13/7/1001

Quote

2.3. Miniature Challenge

 

Due to the miniaturization of light-emitting chips, their luminous efficiency will drop rapidly. The emission efficiency of both blue and green chips will decrease, but compared with the significant decrease of the emission efficiency of red chips, the decrease of efficiency is acceptable in product application. It is difficult to manufacture high-efficiency InGaN-based red Micro-LED chips because with the increase of indium content, the radiation recombination rate is relatively low, and the crystal quality will deteriorate [53]. Due to the low luminous efficiency of red LED chips, the academician Jiang’s research team used efficient InGaN-based orange-red LED chips, which greatly improved the luminous efficiency of red LED chips [54].

 

In addition, ICP etching will cause sidewall defects, which will greatly reduce the light emitting area of Micro-LED chips. As shown in Figure 3, the defect of about 2 μm in the traditional LED chip with the size of 250 μm will not affect the chip performance too much, while the error of 2 μm in the Micro-LED chip with the size of only 5 μm will reduce the external quantum efficiency from about 35% to 10% or even 2%, and the remaining available luminous area of the chip is only 4% of the chip size.

It's not as easy as "just do what you're doing now, but smaller".

[starsmine]

18 hours ago, Edward78 said:

OLEDs burn in & the layers that make the colors die. Why don't they just use RGB LEDs? They can just make the color with out the layer to do it.

they do. but you cant make LEDs small enough for a monitor. 
Mini LEDs are used in large format displays, (think greater then 100 inches)
normal LEDs are used in even larger format displays. (think sports stadiums)

thats where micro-led comes in for normal sized displays. Thats not a viable tech yet.

[Doobeedoo]

Well it's not ready yet, still in development, MicroLED, that is. That will take a while for now OLED is here at least.

[Edward78]

So if they could make CRT thin, would that be better. They would have to go back to fat monitors right?

[Stahlmann]

15 hours ago, Edward78 said:

So if they could make CRT thin, would that be better. They would have to go back to fat monitors right?

No, CRT has been obsolete many reasons, not just the physical size. Modern games don't look anywhere near as good on an old CRT monitor, especially when comparing to modern high refresh rate OLED monitors.

 

For the forseeable future at least, LCD will make up the low-to-mid-range class and OLED will make up the mid to high-end class.

 

MicroLED is probably still decades away from being anywhere near affordable.