What is the principle behind organic light-emitting diodes (OLEDs)?

The principle behind organic light-emitting diodes (OLEDs) is centered on the emission of light through the recombination of electron-hole pairs in organic materials. In OLEDs, when a voltage is applied across the organic materials, electrons are injected from the cathode and holes from the anode. These carriers then move through the organic layers and recombine to form excitons, which are bound states of the electron and hole. When excitons decay, they release energy in the form of light, making OLEDs an efficient source of illumination.

This method is highly advantageous because it allows for the production of bright, vibrant colors with a wide viewing angle and faster response times compared to other display technologies. The organic materials used can be tailored to emit specific wavelengths of light, which is pivotal for creating full-color displays.

The other principles mentioned in the other choices do not apply to OLED technology, as they describe different mechanisms of light emission that are not involved in the operation of OLEDs.