Huixia Xu

Bipolar hosts and non-doped deep-blue emitters (CIEy = 0.04) based on phenylcarbazole and 2-(2-phenyl-2H-1,2,4-triazol-3-yl)pyridine groups

We have designed and synthesized four bipolar materials, TAZ-1Cz, TAZ-2Cz, TAZ-3Cz and TAZ-4Cz, using 2-(2-phenyl-2H-1,2,4-triazol-3-yl)pyridine (TAZ) as an electron-withdrawing group and phenylcarbazole as an electron-donating group. Their rigid molecular structures improve their thermal stability with high glass transition temperatures: 99 °C for TAZ-2Cz, 100 °C for TAZ-3Cz and 103 °C for TAZ-4Cz. Employing TAZ-1Cz, TAZ-2Cz, TAZ-3Cz and TAZ-4Cz as hosts, green phosphorescent organic light-emitting devices (PhOLEDs) with fac-tris(2-phenylpyridine)iridium as an emitter display maximum external quantum efficiencies (EQEs) of 15.8, 15.5, 16.0 and 13.0%, respectively. And blue PhOLEDs hosted by TAZ-1Cz, TAZ-2Cz and TAZ-3Cz achieved maximum current efficiencies of 8.6, 11.0 and 10.6 cd A−1, respectively. Furthermore, non-doped OLEDs using TAZ-1Cz and TAZ-4Cz as emitters exhibit electroluminescence (EL) peaks at 400 and 412 nm with CIE coordinates of (0.16, 0.04) and (0.15, 0.04), which are located in the deep-blue region.

Mixed ligands 8-hydroxyquinoline aluminum complex with high electron mobility for organic light-emitting diodes

A mixed ligands 8-hydroxyquinoline complex (Alq2A) with improved electron mobility was designed for organic light-emitting diodes. The electron mobility in Alq2A was determined via transient electroluminescence (EL) from bilayer devices with structure of indium tin oxide/4,4′-bis[N-(1-naphthyl)-N-Phenyl amino]biphenyl/Alq2A∕LiF∕Al. It was found that the electron mobility in Alq2A is between (2.7and4.4)×10−6cm2∕Vs at electric fields ranging between 1.42×106 and 2.40×106V∕cm, which is higher than that in Alq3. The Alq2A also shows a higher EL efficiency in steady-state EL studies, which is considered to be derived from (1) improved electron mobility, (2) high fluorescene efficiency, and (3) good film-forming.

Stabilizing and activating dopants in ⟨112⟩ silicon nanowires by alkene adsorptions: A first-principles study

The B dopant stability and doping level tunability of ⟨112⟩ silicon nanowires (SiNWs) with alkene adsorption are revealed based on first-principles calculations. It is found that the alkenyl chains favor the middle location of (111) facet, and the B dopants prefer to locate at (110) facet of the ⟨112⟩ SiNW. Interestingly, the B doping levels are activated upon an alkene adsorption which introduces an intermediate energy level. This finding sheds light on how SiNWs can achieve effective doping.

Synthesis and photoelectric properties of a solution-processable yellow-emitting iridium(III) complex

A solution-processable yellow-light-emitting heteroleptic phosphorescent Ir(III) complex of (CzhBTZ)2Ir(fpptz) [CzhBTZ: (2-[2-(6-(9-carbazolyl)hexyl)phenyl]benzothiazole) fpptz: (2-(5-(4-fluorophenyl)-2H-1,2,4-triazol)-3-yl)] was synthesized. Its photophysical, thermal and electroluminescence properties were investigated. Phosphorescent organic light-emitting diodes (PhOLEDs) using (CzhBTZ)2Ir(fpptz) doping in (4,4′-bis(N-carbazolyl)-1,1′-biphenyl) as the emitting layer were prepared by spin-coating with a maximum peak at 533 nm, and International Commission on Illumination (CIE) coordinates of (0.42, 0.56).