Xiaohong Fang

Geometric and electronic structures of new endohedral fullerenes: Eu@C72

The geometric and electronic structures of rare earth metallofullerenes Eu@C72 were investigated using density functional theory (DFT) within a generalized gradient approximation (GGA). The geometric optimization revealed that the most favorable endohedral site for Eu is off-center along the C2 axis on the σv plane pointing to the (5, 5) bond at the fusion of two pentagons. Calculations for electronic structures show that two 6s electrons in Eu transfer to the lowest-unoccupied-molecular orbitals of C72 while 4f electrons remain in Eu.

Optical and electrical properties of [N,N′-bis(salicylidene)-ethylenediamine]zinc as an electroluminescent material

The variability of photoluminescence (PL) and electroluminescence (EL) properties of [N,N′-bis(salicylidene)-ethylenediamine]zinc [Zn(salen)] was investigated. It was found that the PL spectra of Zn(salen) powder are dependent on synthesis temperature, and recrystallization solvent and those of Zn(salen) film are dependent on deposition vacuum degree. The EL properties of Zn(salen) are not only dependent on deposition vacuum degree but also dependent on driving voltage. The variability of PL and EL properties of Zn(salen) can be related to the various molecular geometries of Zn(salen).

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.