LCDs are driven with AC, to prevent electrolytic damage to the thin transparent electrodes. LEDs are driven with DC.

Platinum electrodes

An organic light emitting diode (OLED) is a light-emitting diode (LED) in which the emissive electroluminescent layer is a film of organic compounds which emits light in response to an electric current. This layer of organic semiconductor material is situated between two electrodes. Generally, at least one of these electrodes is transparent.

They are electrodes surgically-implanted into the brain

Electrodes placed inside the cochlear receive the decoded signals. The 22 electrodes allow a range of different pitches to be detected. The electrodes stimulate the hearing receptors.