An effective Friedel-Crafts postfunctionalization of poly(N-vinylcarbazole) to tune carrier transportation of supramolecular organic semiconductors based on π-stacked polymers for nonvolatile flash memory cell

Poly(N-vinylcarbazole) (PVK) and its derivatives are π-stacked polymers of the most important supramolecular organic semiconductors (SOSs), in which semiconducting features are originated from intra-supramolecular interactions. An effective Friedel-Crafts method has been developed to postfunctionalize PVK to a PVK-PF SOS and to tune the fundamental electronic structures and transporting properties of the resulting SOS. Stable nonvolatile flash memory effect from the SOS has been demonstrated in an ITO/PVK-PF/metal sandwich device. The device exhibited an ON/OFF current ratio up to 104, and writing/erasing voltages around +2.2/-2.0 V, respectively. The unique electrical bistability can be attributed to the ordering alignment effect induced by electric field and the hindrance effect arisen from bulky moieties. Thus, PVK-containing complicated 9,9-diarylfluorenes (CDAFs) are promising materials for information storage applications.