What is an organic LED (OLED)?
Because the vast majority of LEDs use inorganic semiconductors, the acronym LED normally refers to inorganic-semiconductor-based LEDs. Some LEDs use organic semiconductors (carbon-based small molecules or polymers), and the acronym OLEDs refers to these organic-semiconductor-based LEDs. They are similar to inorganic-semiconductor-based LEDs in that passing an electrical current through an OLED creates an excited state that can then produce light. OLEDs are less expensive than LEDs, in part because they do not need to be crystalline (or “defect free”). Hence, their fabrication processes are more forgiving, and they can even be applied as large-area coatings on curved, flexible surfaces. However, it is likely that OLEDs will be too fragile to sustain high electrical current density, hence their light output per unit area may be limited. For these reasons, OLEDs may target applications compatible with broad-area light sources, while LEDs target applications compatible with small-area (poi
