OLED and LCD fail in opposite ways

There is a settled way of talking about display technology. It is worth asking how much of it survives contact with the detail.

The structural difference

An LCD has a backlight that is always on behind a layer of crystals that twist to block or pass light through colour filters. An OLED has no backlight; each subpixel is an organic compound that emits light when current passes through it.

Blocking light imperfectly is why LCD blacks appear dark grey, especially in a dark room and at an angle. Emitting no light at all is why OLED blacks are indistinguishable from a switched-off screen.

Contrast, viewing angle and colour

Per-pixel emission gives OLED an effectively unlimited contrast ratio, which is the property people notice first. Because there is no light path through layered filters, OLED holds colour and contrast at steep angles where LCD washes out.

Local dimming zones give LCD much of the contrast benefit by dividing the backlight into regions, at the cost of visible haloing around bright objects on dark backgrounds. The number of zones determines how large those halos are, which is why zone count appears in specifications.

Brightness is where LCD still competes

A backlight can be made very bright cheaply, which matters for a screen used in direct sunlight. OLED brightness is limited by how hard the emitters can be driven without accelerating their decay, so peak brightness is often sustained only over a small portion of the screen. This is why an OLED specification quotes a full-screen figure and a much higher peak window figure.

Under load, a mostly white document on an OLED phone in bright sun is the worst case for the technology.

Ageing is the real divergence

OLED emitters lose efficiency with cumulative use, and the different colour compounds age at different rates. A static element such as a status bar or a channel logo therefore ages its pixels faster, leaving a permanent ghost, which is burn-in. Manufacturers mitigate this by shifting pixels slightly, dimming static regions and compensating in the driver, which reduces rather than removes it.

LCD dims across the whole panel as the backlight ages, which is uniform and far less noticeable.

Flicker is a genuine complaint

Many OLED panels dim by switching pixels on and off rapidly rather than reducing current, because low currents produce inconsistent colour. That pulsing is invisible to most people and causes headaches or eye strain for a minority, particularly at low brightness. Panels using higher switching frequencies or current-based dimming reduce the effect, and vendors have begun advertising this.

Anyone who finds one phone uncomfortable and another fine at the same brightness is probably encountering exactly this.

Figures here are typical rather than guaranteed — check the spec sheet for your part.

Choosing by use rather than by ranking

A screen used for dark content in dim rooms benefits most from per-pixel emission, which is why film viewing favours OLED. A screen showing static interfaces at high brightness for many hours a day is the workload that ages OLED fastest. Newer emitter structures and quantum dot layers have improved OLED brightness and colour considerably, and the underlying ageing mechanism remains.

The short version: neither technology is better in general; they are better at opposite things.

The takeaway

One technology cannot make a perfect black; the other cannot stay identical forever. Pick the failure you mind less.

Understanding the failure mode tells you more than the feature list does.