In plain language
An LCD has a backlight shining through a filter, so black is really very dim grey. Organic light-emitting diode panels have no backlight: each pixel emits light itself and a black pixel is off. Contrast is effectively infinite, and there is no halo around bright objects.
The trade-off is peak brightness. OLED televisions typically reach lower peaks than the best LCDs, which matters for HDR in a bright room.
Why it matters in your setup
Because peak brightness is limited, tone mapping is doing real work on an OLED, and the luminance values advertised in the HDR metadata have a visible effect. Many of the LLDV settings people fiddle with exist precisely to get that mapping right on OLED panels.
Small OLED panels are also common as status displays on AV hardware, where their readability at a glance in a dark rack is the point.
What the DR HDMI 8K does with it
The DR HDMI 8K has a 1-inch 128×64 two-colour OLED on the front. It cycles four info pages: the default page with FRL rate and RX/TX status, the RX EDID page, the TX EDID page and the unit info page with serial, firmware and IP. It is the fastest read on what a chain is doing without opening a browser, and it can be dimmed, rotated 180 degrees or switched off entirely.
Need the hardware?
Open the DR HDMI 8K product page on HDfury.uk.