Aside from the issues you've already mentioned, another problem with RGB OLED is that the blue sub-pixel decays faster than the other two. This is the main reason LG pursued WRGB and Samsung abandoned its RGB OLED TVs, although the latter is still one of the largest manufacturers of AMOLED screens for mobile devices.
The Sony professional OLED monitor, which used a Panasonic panel and is no longer available, used RGB on a 32-inch screen size, but it still only delivered 100% of DCI-P3 and 1,000nits. It also had a shorter lifespan compared to consumer OLED TVs, which is one of the reasons why the professionals are moving to a new Dual LCD monitor for mastering work. The latter will also be brighter, more consistent and won't suffer from image retention or screen burn.
Thanks for a great article Steve.
Overall I think that OLED will remain the best display technology for the next few of years - but unless LG make considerable progress (e.g. someone finally develops a TAFD gen blue emitter) they will be overtaken by improving LCDs (dual layer and/or mini-LED) and eventually by micro-LED when this comes down to mass market prices.
Existing RGBW OLED
To me, the future of OLED is dependent upon improvements in the organic emitter materials - especially for blue. At the moment, blue emitter compounds are "first generation" - and have an efficiency of only around 25% i.e. only 25% of the energy that goes in is converted into light. Red and green have already moved on to "second generation" compounds (which are "doped" with heavy metals) and get nearer 100% efficiency. Lots of companies are trying create new (ideally blue) OLED emitters with high efficiency, high brightness and long lifespan - but it always seems to be a few years away. (Try googling for TADF to see the progress made on this 4th generation emitter for blue.)
One of the issues that seems to be related to OLED lifespan is heat. The Panasonic GZ2000 uses a custom panel with a metal heat sink. That better heat dispersion seems to allow it to go brighter and according to some reviews avoid image retention - which may indicate better resilience to screen burn. So one possible improvement for LG could be the general adoption of passive cooling (heatsinks) or even combine passive and active cooling (fans). While professional displays may use fans for cooling - I think it may be a difficult proposition for consumer displays. Fans would make displays considerably thicker and potentially noisy - although the PC industry has really progressed in the manufacture of quiet fans. Personally I would be happy with a thicker display and quiet fans if it meant that the display had a longer lifespan.
Inkjet Printing
Inkjet printing offers the possibility of more accurate placement and more efficient usage of the OLED emitter compounds. It also offers the possibility of considerably lower production costs than the existing evaporative techniques. This should lead to cheaper OLEDs. However, there is a potentially significant downside:
"Despite major progress, it is maintained that soluble OLED materials (required for inkjet printing) are
less effective than evaporable ones. Ink-Jet printing is also not able to reach the same high densities of evaporation OLED production, which limits its applications for large-area production (TV panels)..."
(
OLED ink jet printing: introduction and market status | OLED-Info)
It is possible that inkjet printing could lead to cheaper OLEDs but with lower brightness and/or shorter lifespan.
Quantum Dot OLED
Quantum dot OLED has been put forward as a potential new self-emissive display technology. Quantum dots are much more efficient at converting light from one colour to another than colour filters (which simply block light) so QD could help boost brightness and lifespan of an OLED.
However, blue being the weakest link is a particular issue for Quantum Dot OLED - as QD-OLED can only be driven by blue OLED emitters.
Quantum Dots convert a light source from one colour to another. However, they only work in
one direction - from high frequency (the blue end of the spectrum) to lower frequencies (toward the red end of the spectrum).
A blue light source can, with quantum dots, create both green and red light.
A green light source could be used to create red light.
A red light source cannot be used to create any other visible colour.
So quantum dot OLEDs can
only use blue to create a full RGB display. I belive that Samsung plan on having a stack of two blue OLED emitters behind each sub-pixel to help increase brightness.