The Synthesis And Properties Study Of The Bipolar-transporting Rare-earth Complexes With Carbazole And Oxadiazole Units

The status of europium (â…¢) / erbium (â…¢) complexes used as electroluminescent materials are reviewed in this dissertation. The europium (â…¢)/ erbium (â…¢) complexes and their electroluminescent properties are carried out in order to solve current problems, such as low luminous efficiency and brightnes in their devices. we designed and synthesized a class of novel bipolar-transporting phenanthroline ligands and their europium (â…¢) complexes and erbium (â…¢) complexes with both hole- transporting carbazole and electron-transporting oxadiazole units. The thermal stability, UV–vis absorption and photoluminescence properties of these europium complexes were investigated. The results are listed below.1. We have beening incorporating both hole-transporting carbazole and electron- transporting oxadiazole groups into the phenanthroline ligands by the growth of flexible side chain length. A series of bipolar-transporting phenanthroline ligands and their europium (â…¢) complexes and erbium (â…¢) complexes were synthesized. The molecular structures of these tuned phenanthroline derivatives with carbazole and oxadiazole groups characterized by ¹H NMR, and their europium complexes and erbium(â…¢) complexes were characterized by element analysis and IR spectra.2. Thermal stability, the UV absorption and photoluminescence (PL) properties of the bipolar-transporting europium (â…¢) complexes with carbazole and oxadiazole groups were investigated. All of these bipolar-transporting europium (â…¢) complexes presented a highly thermal stability, All these bipolar-transporting europium complexes presented an high onset degradation temperatures (Td) for 5% weight loss at more than 300℃, the highest onset degradation temperatures (T_d) for 5% weight loss of europium (â…¢) complexes of Eu(DBM)₃(Bu^tOXD6CzPhen) is at 376℃. All of these bipolar-transporting europium (â…¢) complexes have stronger UV absorption and higher photoluminescence emission. Two intense UV absorption bands are showed at around 286 nm and 351 nm, the high-energy absorption band is attributed toÏ€-Ï€^* transitions of the bipolar-transporting phenanthroline ancillary ligands and low-energy absorption band is attributed to the singlet-singletÏ€-Ï€^* transition of theβ-diketone ligands, and nearly identical red emission with a maximum peak at 614 nm resulting from ⁵D₀→⁷F₂ transitions of the central Eu³⁺ ions in dichloromethane were observed. twofold increased photoluminescent quantum yield compared to the reported tri(dibenzoylmethane) (1,10-phenanthroline) europium (â…¢). This indicates incorpora- ting a bipolar-transporting unit into ancillary ligand of phenanthroline can facilitate the enhancement of emission quantum yield of its europium complexes.3. Thermal stability, the UV absorption and photoluminescence (PL) properties of the bipolar-transporting erbium (â…¢) complexes with carbazole and oxadiazole groups were investigated. All of these bipolar-transporting erbium (â…¢) complexes presented a highly thermal stability, All these bipolar-transporting erbium complexes presented an high onset degradation temperatures (Td) for 5% weight loss at more than 300℃, the highest onset degradation temperatures (T_d) for 5% weight loss of erbium (â…¢) complexes of Er(DBM)₃(FOXD6CzPhen) is at 384℃. All of these bipolar-transporting erbium (â…¢) complexes have stronger UV absorption and higher photoluminescence emission . Two intense UV absorption bands are showed at around 290 nm and 352 nm, the high-energy absorption band is attributed toÏ€-Ï€^* transitions of the bipolar-transporting phenanthroline ancillary ligands and low-energy absorption band is attributed to the singlet-singletÏ€-Ï€^* transition of theβ-diketone ligands. and nearly identical near-infrared emission with a maximum peak at 1535 nm resulting from ⁴I_13/2→⁴I_15/2 transitions of the central Er³⁺ ions in dichloromethane were observed, which is near-infrared emission.This investigation laid a good foundation for further designing of the bipolar-transporting organic binuclear rare-earth complexes and obtaining electro- luminescent materials emitting with their red-emitting PLEDs and near-infrared emitting OLEDs with excellent luminescent properties.