5 research outputs found
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Diacenaphthylene-fused benzo[1,2-b:4,5-b‘]dithiophenes: polycyclic heteroacenes containing full-carbon five-membered aromatic rings
We herein report on an efficient synthesis of diacenaphthylenefused benzo[1,2-b:4,5-b’]dithiphenes and demonstrate that their packing structure in the solid state depends on the substituent groups. These compounds form dimers with their radical cations in high solution concentration and display good field-effect mobility
Dynamic Behaviour Analysis of Turbocharger Rotor-Shaft System in Thermal Environment Based on Finite Element Method
The stable operation of a high-speed rotating rotor-bearing system is dependent on the internal damping of its materials. In this study, the dynamic behaviours of a rotor-shaft system with internal damping composite materials under the action of a temperature field are analysed. The temperature field will increase the tangential force generated by the internal damping of the composite material. The tangential force will also increase with the rotor speed, which can destabilise the rotor-shaft system. To better understand the dynamic behaviours of the system, we introduced a finite element calculation model of a rotor-shaft system based on a 3D high-order element (Solid186) to study the turbocharger rotor-bearing system in a temperature field. The analysis was done according to the modal damping coefficient, stability limit speed, and unbalance response. The results show that accurate prediction of internal damping energy dissipation in a temperature field is crucial for accurate prediction of rotor dynamic performance. This is an important step to understand dynamic rotor stress and rotor dynamic design
AIE-Active Fluorene Derivatives for Solution-Processable Nondoped Blue Organic Light-Emitting Devices (OLEDs)
AIE-Active Fluorene Derivatives for Solution-Processable Nondoped Blue Organic Light-Emitting Devices (OLEDs)
A series
of fluorene derivatives end-capped with diphenylamino
and oxadiazolyl were synthesized, and their photophysical and electrochemical
properties are reported. Aggregation-induced emission (AIE) effects
were observed for the materials, and bipolar characteristics of the
molecules are favored with measurement of carrier mobility and calculation
of molecular orbitals using density functional theory (DFT). Using
the fluorene derivatives as emitting-layer, nondoped organic light-emitting
devices (OLEDs) have been fabricated by spin-coating in the configuration
ITO/PEDOT:PSSÂ(35 nm)/PVKÂ(15 nm)/<b>PhN-OFÂ(</b><i><b>n</b></i><b>)-Oxa</b>(80 nm)/SPPO13Â(30 nm)/CaÂ(8 nm)/AlÂ(100
nm) (<i>n</i> = 2–4). The best device with <b>PhN-OFÂ(</b><b>2</b><b>)-Oxa</b> exhibits a maximum
luminance of 14 747 cd/m<sup>2</sup>, a maximum current efficiency
of 4.61 cd/A, and an external quantum efficiency (EQE) of 3.09% in
the blue region. Investigation of the correlation between structures
and properties indicates that there is no intramolecular charge transfer
(ICT) increase in these molecules with the increase of conjugation
length. The device using material of the shortest conjugation length
as emitting-layer gives the best electroluminescent (EL) performances
in this series of oligofluorenes