Synthesis of Oligosaccharide-Based Block Copolymers with Pendent π-Conjugated Oligofluorene Moieties and Their Electrical Device Applications

We report the synthesis and electric device applications of oligosaccharide-based diblock copolymers consisting of a maltoheptaose (MH) block and a poly(4-oligofluorenylstyrene) block (PStFln, n = 1 or 2), referred to as MH-b-PStFln. MH-b-PStFln was prepared by the Cu(I)-catalyzed click reaction of azido-terminated PStFln (PStFln-N3), which was obtained from the azidation reaction of the bromo-terminated PStFln (PStFln-Br), with excess ethynyl-terminated MH in the THF/DMF mixture solvent. The resulting diblock copolymers self-assembled to spherical microdomains with sub-10 nm sizes in both bulk and thin film state after annealing process. Thereafter, the MH-b-PStFln thin film (∼50 nm) with the self-assembled nanoscale spherical aggregates was used as the charge storage layer for the pentacene-based field-effect transistor type memory devices. The MH-b-PStFln-based devices had the excellent hole mobility (0.25–0.52 cm2 V–1 s–1) and the high ON/OFF current (ION/IOFF) ratio of 107–108, of which the MH-b-PStF...