REVIEWS

Abstract Because of long-range order and high chemical purity, organic crystals have exhibit unique properties and attracted a lot of interest for application in solid-state lasers. As optical gain materials, they exhibit high stimulated emission cross sec-tion and broad tunable wavelength emission as similar to their amorphous counterpart; moreover, high purity and high order give them superior properties such as low scattering trap den-sities, high thermal stability, as well as highly polarized emis-sion. As electronic materials, they are potentially able to sup-port high current densities, thus making it possible to realize current driven lasers. This paper mainly describes recent re-search progress in organic semiconductor laser crystals. The building molecules, crystal growth methods, as well as their stimulated emission characteristics related with crystal struc-tures are introduced; in addition, the current state-of-the-art in the field of crystal laser devices is reviewed. Furthermore, re-cent advances of crystal lasers at the nanoscale and single crystal light-emitting transistors (LETs) are presented. Finally, an outlook and personal view is provided on the further devel-opments of laser crystals and their applications. Functional organic single crystals for solid-state laser application