ИСТИНА

Organic field effect transistors (OFETs) are key elements for various emergent organic electronic devices such as integrated circuits, displays, sensors, storage devices, photodetectors and light-emitting devices, which are essential parts of lightweight, flexible and transparent high-tech devices. The progress in n-channel OFETs is not so impressive as compared to that of p-channel ones. This is partially related to difficulties with creation of organic semiconductor materials with low energy values of LUMO (lowest unoccupied molecular orbital) energy, which typically should be lower than –4.0 eV. Such LUMO energy values ensure stability of an organic semiconductor to air oxidation and facilitate electron injection . Owing to combination of chemical and thermal stability , stacked molecular packing and efficient electron transport, naphthalene diimides derivatives (NDIs) are promising materials for n-channel OFETs. In this study, we investigate the effect of fluorine atom in p- position of the phenyl rings of N,N’-diphenyl-1,4,5,8-naphthalene-tetracarboxylic diimide (Ph-NDI) on physicochemical properties, crystal packing and charge mobility in the crystalline NDI derivatives. Fig. 1. ESP mapped on Hirshfeld surfaces for Ph-NDI and p-FPh-NDI crystals. Our research shows that the minor change in electrostatic potential (ESP) distribution after the fluorination results in altering the molecular packing from planar one to herringbone one (Fig.1). As a result, changes in the crystal packing results in a slight increase of calculated charge-carrier mobility (by ~20%). This increase results from the increase of the distance between the molecular centers along the main charge transport direction, while the corresponding charge transfer integral do not change significantly. We anticipate that the obtained results are important for rational design of organic semiconductors with improved electron transport. This work was partially supported by RFBR (projects № 19-32-50003 and № 18-52-45024).