A couple of months ago, Samsung release the Galaxy S5 LTE-A, that sports the company's latest AMOLED panel - a 5.1" QHD (2560x1440) Super AMOLED. Anandtech posted a long review of this new phone, and they find that the display is actually a little bit more efficient than the 5.1" FHD panel used in the GS5, even though it sports a higher resolution (which usually means a less efficient display as the aperture ratio gets smaller.
Anandtech further says that Samsung told them they switched to a new, improved emitter material for the new QHD panel, which explains the increased efficiency. This is interesting as the QHD display was released only a few months after Samsung started producing the FHD panel, which by itself was 27% more efficient than the previous generation panels - also due to more efficient OLED materials.
In April it was reported that Samsung's Cheil Industries (now Samsung SDI) announced it will start supplying Samsung Display with phosphorescent green host for their OLED displays. It was suggested that these new host may be more efficient than UDC's own green hosts. There's no evidence that this is so, however (Cheil's hosts are supposedly cheaper than UDC's). But now it is specifically reported that Samsung adopted new emitter materials. UDC mentioned a few months ago that Samsung switched to a new green PHOLED emitter, but it was thought that this was for the FHD display.
So it may be the Samsung adopted another new PHOLED emitter (maybe a new red, or an ever newer green) from UDC. Or it may be that they adopted a better fluorescent blue. Or it may be that this report is simply not accurate and Samsung's new emitter comment relates to the original FHD panel used in the GS5.
Source: AnandTech
Disclaimer: the author of this post holds share in UDC
Comments
But if you're trying to achieve the same brightness with less aperture, you need to drive the OLEDs higher which is less efficient...
That is one of the good thing about OLED that the display resolution does not have a significant impact on the power unlike LCD.
At that current level the OLED efficiency does not chagne.
If you increase OLED resolution, generally aperture ratio decreases, and so for the same overall screen brightness, individual sub-pixels need to operate at higher brightness/luminance. At typical luminance levels, the luminous efficiency (cd/A) vs luminance curve is quite flat, so change of aperture has little effect on luminous efficiency. However, to get to higher luminance level, a slight increase in voltage will also be needed, thereby reducing overall power efficiency.
I agree with you if the apperture ratio drops. I have not seen the panel, so I cannot comment on the apperture raio. However, the change in apperture ratio has been negligible so far (due to different pixel arrangemetns for higher PPI) which means the change in power due to resolution is not significant either.
I can understand why higher resolution would require more power from an LED backlight. There's less space for the light to pass. For AMOLED, though, wouldn't each of the smaller pixels require proportionally less power? I.e., more pixels covering a slightly smaller area on the same size screen should result in slightly less power draw.