Luxi Tan

Thieno[3,4-c]Pyrrole-4,6-Dione and Dithiophene-Based Conjugated Polymer for Organic Field Effect Transistors: High Mobility Induced by Synergic Effect of H-Bond and Vinyl Linkage.

Here, a conjugated polymer VTTPD based on thieno[3,4-c]pyrrole-4,6-dione (TPD) and dithiophene with vinyl as linker is synthesized and characterized. Electrochemical and optical studies indicate the LUMO and HOMO energies of the polymer are -3.70 and -5.39 eV. Theoretical calculation with density functional theory suggests that H-bonds are formed between the TPD carbonyl (O) and its neighboring vinyl (H) which benefit the planarity and π-conjugation of the polymer backbone. Bottom contact bottom gate organic field effect transistor devices based on VTTPD are fabricated and examined in air. After annealing at 160 °C, the devices exhibit excellent performance of μh = 0.4 cm(2) V(-1) s(-1) , Ion/off = 10(6) , Vth within -10 V to -5 V. Thin film morphologies before and after the annealing process are also investigated with XRD and AFM.

A vinyl flanked difluorobenzothiadiazole–dithiophene conjugated polymer for high performance organic field-effect transistors

Fluorine containing conjugated polymers have been widely applied in high performance organic solar cells, but their use in field-effect transistors is still quite limited. In this work, a conjugated polymer PTFBTV based on difluorobenzothiadiazole (DFBT) and dithiophene was synthesized, utilizing multiple vinylene as linkers. The polymer exhibits a relatively high hole mobility up to 2.0 cm2 V−1 s−1 compared with the reported DFBT–oligothiophene based polymers, yet its structural complexity is much simpler. The polymer thin film exhibits a typical ‘face on’ molecular orientation. A single crystal of its monomer revealed a non-covalent intramolecular contact between fluorine and the neighbouring proton, which strengthens the backbone co-planarity. Meanwhile an intermolecular F⋯F contact was also observed, which might cause rather scattered lamellar crystallinity for PTFBTV in the solid state.

Controllable Synthesis of Hierarchical Rose-Like MnCo2O4 Spinel as Lithium-Ion Anode Materials

Hierarchical rose-like structured MnCo₂O₄ spinel was synthesized via a facile solvothermal process using polyvinyl pyrrolidone (PVP) as the soft template, which was characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), etc. When evaluated as the anode materials for lithium ion batteries, the as-synthesized MnCo₂O₄ spinel exhibited excellent cycling performance and rate capacity. The initial discharge and charge capacity reached 1502 mA·h·g-1 and 1131 mA·h·g-1 at the current density of 100 mA·g-1, respectively.

A new red fluorophore with aggregation enhanced emission by an unexpected “One-step” protocol

In this work, a triphenylamine-benzothiadiazole-based new fluorophore is obtained from a facile “one-step” protocol. A possible reduction mechanism is proposed, and an amine containing α-H plays a key role in the reduction reaction. The resultant product A1H2 exhibits bright red emission in solid state, with an absolute quantum yield of 44.5%. Aggregation induced emission enhancement of A1H2 is also observed with the increased water fraction in THF-H2O mixture. The nanoparticles of A1H2 reveal good stability and biocompatibility, which are successfully applied in cellular cytoplasm imaging.

Vinylene spacer effects of benzothiadiazole–quarterthiophene based conjugated polymers on transistor mobilities

In this work we aim to investigate the relationships among the ratios of vinyl linker, crystallinity and charge carrier mobility in a series of benzothiadiazole–quarterthiophene based conjugated polymers. Four polymers, PB4TV0, PB4TV1, PB4TV2 and PB4TV3, containing 0 to 3 vinyl linkers in the repeating unit were synthesized, and their corresponding bottom gate/bottom contact organic field effect transistors were fabricated and examined. The results manifest escalating hole mobilities along the increasing ratio of vinyl linker, with PB4TV3 reaching a high hole mobility up to 0.36 cm2 V−1 s−1. On the other hand, further investigations have revealed a gradual reduction in the crystallinity with rising vinyl ratio after a slight enhancement at first. The difference between the mobility and crystallinity variation tendency is caused by the combined influences of intra-chain charge transport enhancement and the conformational isomerization nature of the vinyl linker, which could provide new thoughts in designing high performance conjugated polymers for OFETs in future.