ИСТИНА

Organic semiconductors are key functional materials for creating varoius types of field-effect transistors – organic field-effect transistors (OFETs), electrolyte gated organic field-effect transistors (EGOFETs) or organic light emitting transistors (OLETs). Their main property – field effect mobility – depends critically on the chemical structure, frontier energy levels, phase behaviour, crystal packing and processing techniques applied for preparation of the devices. In particular, good solubility and film forming properties are very important for solution processing of organic semiconductors. This can be achieved by rational design of solubilizing chains, including linear or branched alkyl, alkoxy-, alkyithio- and other substituents on particular positions of conjugated aromatic or heteroaromatic cores responsible for the semiconductor properties. Recent advances in organic chemistry allows synthesizing a great variety of organic compounds possessing semiconductor properties. The highest field-effect mobility amoung them show annulated molecules or those containing both annulated and linearly conjugated fragments. The latter class of organic semiconductors combine high mobility and bright luminescence in the bulk that is very promising for their application as active layers in OLETs. Tuning the energy levels of frontier molecular orbitals and bandgap in organic semiconductors via terminal substitution allows switching from the p-type to ambipolar and to the n-type OFETs. This tutorial lecture considers classification and particular examples of high mobility organic semiconductors, peculiatities of their molecular design and chemical structures, physico- chemical properties as well as application in vatious types of field effect transistors – OFETs, EGOFETs and OLETs. Both literature examples and organic semiconductors synthesized in ISPM RAS will be discussed. Special attention will be devoted to the correctness of field- effect mobility values extraction and reporting taking into account various types of nonlinearities in OFET transfer characteristics according to Podzorov et al. Peculiarities of the active layer formation for EGOFETs and their stability will be also highlighted.