ABSTRACT
This chapter provides the widest perspective on the rich variety of materials that are available so far to develop organic lasers, revisiting the most iconic and well-established compounds but focusing on the newest developments. It begins by dyes with stunning efficiencies or biological activity, to organic semiconductors approaching their ultimate goal—electrical pumping. The chapter discusses the organic compounds into four major classes: dyes, molecular crystals, molecular glasses and conjugated polymers. Since the discovery of the first organic dyes emitting laser light, thousands of different organic systems have been shown to emit laser light in a rich variety of situations and conditions. Most candidates for organic active materials present relatively high fluorescent quantum yields in diluted solution, but this is reduced, or even nullified, at high concentrations due to excitation self-annihilation, thus increasing the laser threshold and reducing the conversion efficiency. Dyes are the eldest and most mature compounds among all the available organic laser materials.
