ИСТИНА

Organic light-emitting transistor (OLET) — one of the "youngest" organic electronics devices — has a number of advantages over the more traditional organic light-emitting diodes (OLEDs), which are already widely used in displays of portable devices and advanced TV screens. For example, OLET can be much brighter, and the light can be outcoupled from it much more efficiently. Moreover, OLETs are the most promising platform for injection organic lasers, which have still to be demonstrated. An ideal OLET is per se an ambipolar organic field-effect transistor (OFET) with a totally emissive active layer and Ohmic contacts. Taking in account that the charge transport in OFETs occurs within a few semiconductor monolayers adjacent to the semiconductor-dielectric interface, a perfect OLET active layer would be a molecularly thin (2D) single crystal of a brightly luminescent ambipolar semiconductor. Indeed, the high structural quality of semiconductor single crystals provides their superior electrical performance, and the 2D active layer is very beneficial for OLET to get rid of waveguiding effects that reduce the light output from thin film and 3D-single-crystal devices. In addition, 2D OLETs have a high potential for various sensing applications. However, combination of bright luminescence and efficient ambipolar charge transport in one material is a challenge. Moreover, 2D emissive semiconductor single crystals are an almost unexplored field of research. In this presentation, recent development of brightly fluorescent 3D and 2D semiconductor single crystals will be overviewed. The most attention is paid to single crystals based on thiophene-phenylene and furan-phenylene co-oligomers. Molecular (self)doping is shown to be an efficient approach to increase and control fluorescence from organic semiconductor single crystals.1,2 Monolayer single crystals of thiophene-phenylene co-oligomers showing the electrical performance not inferior to that of the 3D ones will be presented.3 Hurdles on the way to efficient OLETs will be discussed. This work is supported by Russian Science Foundation (project № 18-12-00499).