A new category of deep-absorbing small molecules is developed. Optimized devices driven by mixed additives show a remarkable short-circuit current of ≈20 mA cm(-2) and a highest power conversion efficiency of 9.06%. A multi-length-scale morphology is formed, which is fully characterized by resonant soft X-ray scattering, high-angle annular dark film image transmission electron microscopy, etc.

Multi-Length-Scale Morphologies Driven by Mixed Additives in Porphyrin-Based Organic Photovoltaics.

Supramolecular block copolymers: graphene oxide composites for memory device applications

It is discovered that the memory-type behaviors of novel carbohydrate-block-polyisoprene (MH-b-PI) block copolymers-based devices, including write-once-read-many-times, Flash, and dynamic-random-access-memory, can be easily controlled by the self-assembly nanostructures (vertical cylinder, horizontal cylinder, and order-packed sphere), in which the MH and PI blocks, respectively, provide the charge-trapping and stretchable function. With increasing the flexible PI block length, the stretchability of the designed copolymers can be significantly improved up to 100% without forming cracks. Thus, intrinsically stretchable resistive memory devices (polydimethylsiloxane(PDMS)/carbon nanotubes(CNTs)/MH-b-PI thin film/Al) using the MH-b-PI thin film as an active layer is successfully fabricated and that using the MH-b-PI12.6k under 100% strain exhibits an excellent ON/OFF current ratio of over 106 (reading at −1 V) with stable V set around −2 V. Furthermore, the endurance characteristics can be maintained over 500 cycles upon 40% strain. This work establishes and represents a novel avenue for the design of green carbohydrate-derived and stretchable memory materials.

Conception of Stretchable Resistive Memory Devices Based on Nanostructure-Controlled Carbohydrate-block-Polyisoprene Block Copolymers

A poly(fluorene-thiophene) donor with a tethered phenanthro[9,10-d]imidazole acceptor for flexible nonvolatile flash resistive memory devices

Multilevel nonvolatile transistor memories were fabricated with inserted electret dielectric of star-shaped poly((4-diphenylamino)benzyl methacrylate). The devices could be controllably charged and retain the digital states even when the supply voltage was removed. The multilevel data storage characteristics by applying different gate voltages suggested novel ‘write-many-read-many memory’ behaviors.

Multilevel nonvolatile transistor memories using a star-shaped poly((4-diphenylamino)benzyl methacrylate) gate electret

Resistive switchable memory devices were fabricated using self-assembled composite thin films of asymmetric poly(styrene-block-4-vinylpyridine) (PS-b-P4VP) block copolymers (BCP) and fullerene derivatives (PCBM). L1 (with a longer PS block) was comprised of discrete vertical P4VP nanocylinders embedded within the PS matrix whereas L2 (with a longer P4VP block) revealed a reverse morphology with a horizontal orientation. They were used to control the spatial location or distribution of the PCBM and the resultant memory characteristics. The devices with ITO/BCP:PCBM/Al configurations exhibited variable multi-electronic characteristics, changing from insulating to bistable memory switching and highly conducting, as the PCBM content increased. The L1:PCBM memory device showed non-volatile write-once-read-many-times (WORM) memory behavior but the L2:PCBM device exhibited a volatile nature of static random access memory (SRAM). Both L1 and L2:PCBM composite devices revealed the improved switching performance upon solvent annealing procedures of the composite thin film. Our results suggested that the controlled morphology of the BCP/PCBM composite could create nanoscale charge-storage elements for a high density memory device with a reduced bit cell size.

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Jhao Cheng Chen

Papers

Tunable electrical memory characteristics by the morphology of self-assembled block copolymers:PCBM nanocomposite films