The second-generation p-i-n OLEDs

Organic light emitting diodes (OLEDs) have attracted enormous attention across the world during the past two decades, due to their competitive applications in the fields of flat-panel displays and general lighting. Currently, active-matrix OLEDs (AMOLEDs) have been successfully made small-sized and high-resolution displayers which are being mostly adopted in smart phones. Unlike inorganic LEDs which are point light sources on rigid substrates and emit some blue ray harmful to human health, OLEDs are surface light sources on their hard or flexible substrates and emit warm-white light pleasant to human's eyes, therefore thought as a promising candidate to revolutionize the indoor general lighting concepts and apparatuses.