JOLED announced that it started to sample 21.6" 4K OLED monitors. These monitors, demonstrated in March 2017, feature a 3840x2160 resolution (204 PPI), a brightness of 350 cd/m2 and a contrast ratio of 1,000,000 : 1. The panel thickness is 1.3 mm and the weigh is 500 grams.
JOLED aims to start mass producing these panels in 2019, but will also attempt to sell these to the medical market even in low-volume production out of its current 4.5-Gen pilot production line.
JOLED was established in August 2014 by Japan Display, Sony and Panasonic with an aim to become an OLED medium display (10-30 inch) producer. JOLED is using OLED printing technologies (originally developed at Panasonic) and a top-emission structure (probably Sony's Super-Top-Emission structure).
JOLED is using soluble OLED materials - but it not clear what kind of materials exactly. Back in 2013 Panasonic was using Sumitomo's P-OLED materials, but it is also possible that JOLED is using other materials. Merck recently announced that its soluble emitters have achieved efficiency and lifetime parity with evaporable OLEDs. For more information on JOLED's technology click here.
In March 2017 JOLED also demonstrated several other OLED prototypes - including a flexible FHD panel (shown below), a 12.2" FHD (180 PPI) panel and a 19.3" 4K panel.
Towards the end of 2016 Japan Display (JDI) paid around $100 million USD to INCJ to raise its stake at JOLED to over 50%. This deal values JOLED at around $300 million.