[coder543]

I have used both LCD and OLED smartphone displays at incredibly low brightness in pitch black rooms for a long time, and I have to completely disagree.

On the other hand, E-Ink is amazing in sunlight, where smartphone displays can't get sufficiently bright.

[singularity2001]

Which smartphone displays can you set to 'incredibly low brightness'? all iPhones and Androids I've used are like bright flashlights when the lights are switched off.

[coder543]

It's all relative. I don't own a single flashlight that can be set dimmer (or anywhere close to as dim) as my iPhone XS Max is at minimum brightness on a white page. If the XS Max is showing mostly-dark content, the amount of light emitted is really tiny at minimum brightness because of that OLED display.

On the various Android devices I've owned, I've used a useful app called Screen Filter that adds a translucent layer on top of all apps to dim the screen beyond the artificial manufacturer-imposed minimum brightness, which worked especially well on OLED Android phones, but also LCDs worked fine too.

[orbital-decay]

Presumably, all or most Xiaomi phones. I've never used one for long, but the lowest backlight level in those I tested (Redmi Note 2, Mi A1, RN5) was comparable to the level 2 or 3 of the Kindle Paperwhite frontlight. (level 1 is a failsafe option since the Paperwhite has no physical buttons, it's not meant for reading, being too dark even for a pitch black room)

That said, I don't think reading in poor lighting conditions is a good idea for your eyes, no matter the technology.

[Obi_Juan_Kenobi]

You can use an app to reduce the brightness further. I've been using Twilight on Android, and it does indeed get much dimmer. You will certainly lose some image quality/performance, but it's very nice for viewing in a dark room.