Pei-Yang Gu

Synthesis, characterization, and nonvolatile ternary memory behavior of a larger heteroacene with nine linearly fused rings and two different heteroatoms.

To achieve ultrahigh density memory devices with the capacity of 3(n) or larger, organic materials with multilevel stable states are highly desirable. Here, we reported a novel larger stable heteroacene, 2,3,13,14-tetradecyloxy-5,11,16,22-tetraaza-6,10,17,21-tetrachloro-7,9,18,20-tetraoxa-8,19-dicyanoenneacene (CDPzN), which has two different types of heteroatoms (O and N) and nine linearly fused rings. The sandwich-structure memory devices based on CDPzN exhibited excellent ternary memory behaviors with high ON2/ON1/OFF current ratios of 10(6.3)/10(4.3)/1 and good stability for these three states.

Recent progress in organic resistance memory with small molecules and inorganic–organic hybrid polymers as active elements

Organic resistance memory has attracted a lot of attention due to its high scalability, flexibility, easy processing, low fabrication cost, etc. Organic small molecules, which possess well-defined structures and more accurate experiment-simulation matching, have been widely explored as active materials for application in organic resistance memory. In addition, inorganic–organic hybrid polymers are expected to have charming resistive switching properties because they can potentially combine the advantages of both inorganic materials and organic polymers. This review presents the recent progress of organic resistance memory based on several families of organic small molecules and some typical inorganic–organic hybrid polymers, and discussion of their structure–property relationships.

Synthesis, physical properties, and light-emitting diode performance of phenazine-based derivatives with three, five, and nine fused six-membered rings.

Realizing the control of emission colors of single molecules is very important in the development of full-color emitting materials. Herein, three novel phenazine derivatives (2,3,7,8-tetrakis(decyloxy)phenazine (2a), 2,3-didecyloxy-5,14-diaza-7,12-dioxo-9,10- dicyanopentacene (2b), and 2,3,13,14-tetradecyloxy-5,11,16,22-tetraaza-7,9,18,20-tetraoxo-8,19-dicyanoenneacene (2c)) have been successfully synthesized and fully characterized. Compound 2c can emit blue light in toluene solution (450 nm), green light in the powder/film state (502/562 nm), and red light in the 2c/TFA state (610 nm). The OLED with 2c emits a strong green light at a peak of 536 nm with a maximum luminance of the OLED of about 8600 cd m(-2), which indicates that 2c could be a promising fluorescent dye for OLED applications.

Nanostructured Conjugated Polymers for Energy-Related Applications beyond Solar Cells.

To meet the ever-increasing requirements for the next generation of sustainable and versatile energy-related devices, conjugated polymers, which have potential advantages over small molecules and inorganic materials, are among the most promising types of green candidates. The properties of conjugated polymers can be tuned through modification of the structure and incorporation of different functional moieties. In addition, superior performances can be achieved as a result of the advantages of nanostructures, such as their large surface areas and the shortened pathways for charge transfer. Therefore, nanostructured conjugated polymers with different properties can be obtained to be applied in different energy-related organic devices. This review focuses on the application and performance of the recently reported nanostructured conjugated polymers for high-performance devices, including rechargeable lithium batteries, microbial fuel cells (MFCs), thermoelectric generators, and photocatalytic systems. The design strategies, reaction mechanisms, advantages, and limitations of nanostructured conjugated polymers are further discussed in each section. Finally, possible routes to improve the performances of the current systems are also included in the conclusion.

1,5,9-Triaza-2,6,10-triphenylboracoronene: BN-Embedded Analogue of Coronene

A novel BN-fused coronene derivative 1,5,9-triaza-2,6,10-triphenylboracoronene (1) has been successfully synthesized in one step from 2,3,6,7,9,10-hexamethoxy-1,5,9-triamino-triphenylene. Compound 1 has been investigated using photophysical, electrochemical, and molecular simulation methods. Interestingly, three phenyl groups at B centers in compound 1 can be replaced by hydroxyl units stepwise through hydroxylation in wet organic solvents, leading to changes in the packing and physical properties.

The AIEE effect and two-photon absorption (TPA) enhancement induced by polymerization: synthesis of a monomer with ICT and AIE effects and its homopolymer by ATRP and a study of their photophysical properties

A monomer including pyrazoline and l,8-naphthalimide moieties and its homopolymer were prepared by atom transfer radical polymerization (ATRP). The emission of the monomer can be tuned by choosing solvents with different polarities or aggregation-induced emission (AIE). The rotation of the fluorophore of the homopolymer was further limited by both the side chain and the flexible main chain, resulting in emission enhancement in strong polar solution and aggregation-induced emission enhancement (AIEE) characteristics. More interestingly, compared to that of the monomer, the two-photon absorption (TPA) property of the homopolymer is much more enhanced both in toluene and aggregates. This is attributed to the amplification effect of the polymer chain. This may become a new and promising method with which to prepare TPA polymers.

An Azaacene Derivative as Promising Electron-Transport Layer for Inverted Perovskite Solar Cells

It is highly desirable to develop novel n-type organic small molecules as an efficient electron-transport layer (ETL) for the replacement of PCBM to obtain high-performance metal-oxide-free, solution-processed inverted perovskite solar cells (PSCs) because this type of solar cells with a low-temperature and solution-based process would make their fabrication more feasible and practical. In this research, the new azaacene QCAPZ has been synthesized and employed as non-fullerene ETL material for inverted PSCs through a solution-based process without the need for additional dopants or additives. The as-fabricated inverted PSCs show a power conversion efficiency up to 10.26 %. Our results clearly suggest that larger azaacenes could be promising electron-transport materials to achieve high-performance solution-processed inverted PSCs.

Synthesis of tetranitro-oxacalix[4]arene with oligoheteroacene groups and its nonvolatile ternary memory performance

To achieve ultra-high density memory devices with a capacity of 3n or larger, a novel larger and stable oxacalix[4]arene, 4N4OPz, is reported. 4N4OPz exhibited excellent ternary memory behavior with high ON2/ON1/OFF current ratios of 108.7/104.2/1, low switching threshold voltage of −1.80 V/−2.87 V, and good stability for these three states.

Initiator-lightened polymers: preparation of end-functionalized polymers by ATRP and their intramolecular charge transfer and aggregation-induced emission

A simple strategy to prepare AIE polymers is invented using an AIE initiator for atom transfer radical polymerization. The dual photoresponse by intramolecular charge-transfer and luminogen aggregation of the initiator is well-realized and even enlarged after polymerization, due to the linkage of polymer chains.

Self-Healing Behavior in a Thermo-Mechanically Responsive Cocrystal during a Reversible Phase Transition

The molecular-level motions of a coronene-based supramolecular rotator are amplified into macroscopic changes of crystals by co-assembly of coronene and TCNB (1,2,4,5-tetracyanobenzene) into a charge-transfer complex. The as-prepared cocrystals show remarkable self-healing behavior and thermo-mechanical responses during thermally-induced reversible single-crystal-to-single-crystal (SCSC) phase transitions. Comprehensive analysis of the microscopic observations as well as differential scanning calorimetry (DSC) measurements and crystal habits reveal that a thermally-reduced-rate-dependent dynamic character exists in the phase transition. The crystallographic studies show that the global similarity of the packing patterns of both phases with local differences, such as molecular stacking sequence and orientations, should be the origin of the self-healing behavior of these crystals.