Organic optoelectronics

Summary form only given. This tutorial reviews the important properties and performance characteristics of devices such as LEDs, photodiodes, transistor-based displays, and lasers. Organic semiconductor based photoconductors are extensively used in xerographic photoreceptors and constitute the first large market for organic semiconductors. Small molecule and conjugated polymer light-emitting diodes are on the verge of large-scale commercialization, with the first products having recently appeared. The past few years have seen impressive strides being made in improving the efficiency and stability of such devices. Luminous efficiencies >40 lumens/watt have been attained. High-efficiency blue, green, red, and white LEDs have been reported with both small-molecule based materials systems and conjugated polymers. Organic-based photodiodes and solar cells based on photo-induced charge transfer have also been the subject of research and internal quantum efficiencies of >50% have been reported. Flexible organic transistor circuits have been used as backplanes in novel paper-like electronic displays. Injection lasers, the holy grail of organic optoelectronics, have turned out to be difficult to realize until very recently. Absorption losses caused by injected carriers and low carrier mobilities are some of the problems, while the 4-level nature of organic semiconductors and high gain are some of the advantages.