Liquid Crystalline Rylenediimides with Highly Order Smectic Layer Structure as a Floating Gate for Multiband Photoresponding Photonic Transistor Memory

With the growing demands of light fidelity technology, photonic transistor memory has gained considerable attention for next-generation optoelectronic devices. In this work, alkylated rylenediimides of 2,9-diphenethylanthra[2,1,9-def:6,5,10-d“e”f]diisoquinoline-1,3,8,10(2H,9H)-tetraone (C8-PDI) and 2,7-dioctylbenzo[lmn][3,8]phenanthroline-1,3,6,8(2H,7H)-tetraone (C8-NDI), and pyromellitic diimide of 2,6-dioctylpyrrolo[3,4-f]isoindole-1,3,5,7(2H,6H)-tetraone (C8-PMDI) have been used as floating gate electrets in the photonic field-effect transistor-type memory. The structure-optics-performance relationship of these rod-like molecules has been systematically studied, and the memory device exhibited a decent response to photowriting and electrical erasing processes, owing to the 3D ordered smectic layer structure and brickwork stacking. Therefore, an evenly distributed photogating moiety, efficient exciton dissociation associated with decent carrier tunneling and charge trapping can be obtained. Among them, the sought-after C8-NDI presents favorable energy level alignment, multiband photoresponding, and an optimal block ratio. The fabricated photonic memory with C8-NDI electret presented a remarkable memory switchability with a memory ratio of 104 and a stable memory ratio of 105 over 10,000 s. To the best of knowledge, this is the first work to utilize rylenediimides based liquid crystals as an efficient charge blocking electret, and these findings open an avenue for designing rod-like molecules with highly ordered liquid crystalline properties in the ultrafast photomemory devices. ? 2021 Wiley-VCH GmbH