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High-Performance Nonvolatile Transistor Memories of Pentacence Using the Green Electrets of Sugar-based Block Copolymers and Their Supramolecules



Reported here are the nonvolatile electrical characteristics of pentacene-based organic field-effect transistor (OFET) memory devices created from the green electrets of sugar-based block copolymer maltoheptaose-block-polystyrene (MH-b-PS), and their supramolecules with 1-aminopyrene (APy). The very hydrophilic and abundant-hydroxyl MH block is employed as a charge-trapping site, while the hydrophobic PS block serves as a matrix as well as a tunneling layer. The orientation of the MH nanodomains could be well controlled in the PS matrix with random spheres, vertical cylinders, and ordered horizontal cylinders via increasing solvent annealing time, leading to different electrical switching characteristics. The electron-trapping ability induced by the horizontal-cylinder MH is stronger than those of the random-sphere and vertical-cylinder structures, attributed to the effective contact area. The electrical memory window of the device is further improved via the supramolecules of hydrogen-bonding 1-aminopyrene to the MH moieties of MH-b-PS for enhancing the hole-trapping ability. The optimized device using the horizontal cylinders of the supramolecule electret exhibits the excellent memory characteristics of a wide memory window (52.7 V), retention time longer than 104 s with a high ON/OFF ratio of >105, and stable reversibility over 200 cycles. This study reveals a new approach to achieve a high-performance flash memory through the morphology control of sugar-based block copolymers and their supramolecules.