ИСТИНА

Extensive research in the field of organic semiconductors demonstrates their great potential for different electronic applications. Enhancement of charge transport properties of organic semiconducting materials is still challenge which can be overcome by effective controlling molecular doping. A large variety of organic molecules can serve as dopants, however, doping mechanism and efficiency still cannot be reliably predicted because of complexity of composite materials, high level of energetic disorder, strong effects of film nanomorphology, etc. Fluorinated fullerenes are one of the scantily explored strong electron acceptors which can be easily obtained via direct fluorination of fullerenes with molecular fluorine or metal fluorides. Having in hands fluorinated fullerene C60F48 (Fig. 1), which is a strong acceptor with the LUMO energy of 5.2 eV and yet found to be an effective dopant for small-molecule benzothiophene derivative, we start our research with doping of widespread conjugated polymer, poly(3-hexylthiophene-2,5-diyl) (P3HT) and its composites with carbon nanotubes. We investigate influence of dopant concentration, P3HT/carbon nanotubes ratio on optic properties, electronic characteristics and morphologies of fabricated p-doped materials. UV-Vis absorption spectra of P3HT and fluorinated fullerene in o-dichlorobenzene solutions demonstrate appearance and arising of new absorption features in linear dependence with acceptor concentration due to absorption either of fluorinated fullerene anions or formation of charge transfer complexes between donor and acceptor species. Further evidence of interactions comes from quenching of P3HT fluorescence upon addition of C60F48. The devices with ITO/p-doped material/Ag architecture are constructed, and their morphology is studied by means of AFM. Space-charge limited current measurements demonstrate enhancement charge mobility in P3HT and P3HT/CNT composites of ca two order of magnitude through addition of even a small amount of C60F48 (ca 2 wt%). The reported study was funded by RFBR according to the research project № 18-53-06009.