一种新型铕配合物的有机电致发光性能

研究了一种新型的稀土金属铕配合物EuL₁L₂的光致发光和电致发光特性。将这种铕配合物掺杂到PVK:PBD中,制备成结构为ITO/PVK:PBD:EuL₁L₂/PBD/Alq₃/Mg:Ag/Ag的器件,对其电致发光性能进行研究,发现Eu³⁺离子和Alq₃的相对发光强度随PVK:PBD:EuL₁L₂和Alq₃之间的激子阻挡层PBD的厚度变化而变化,通过调节PBD的厚度,得到了色纯度较高的红色电致发光器件,其光谱具有显著的Eu³⁺离子的光谱特征。

Organic Electroluminescent Devices Using a New Organic Complex of Rare-earth Europium EuL1L2

Organic light-emitting diodes(OLEDs) are of great interest,since they efficiently emit light in the visible region and give promising applications.Full color displays require pure red,green and blue emission.However,the broad nature of the luminescent spectra of these organic molecules leads to the poor luminescent purity,which is dull and,thus,not suited for actual display applications.Rare earth complexes are very suitable for full color displays because of their sharp emission bands.In addition,EL efficiency based on rare earth complex is not limited by spin ruling,since their photoluminescence results from the formation of both singlets and triplets of the ligands,and then transferring energy to lanthanide cores.Theoretically,the upper limit of inner quantum efficiency can reach 100%,which is four times higher than that of the devices using other fluorescent material.For OLEDs,the development of high-perfor-(mance) red emission is still much in demand compared with both green and blue emission.A new organic complex of rare-earth europium(Eu) EuL₁L₂ was reported.The electroluminescence and photoluminescence of this Eu complex were studied.The multilayer devices with the structure of ITO/PVK:PBD:EuL₁L₂/PBD/Alq₃/Mg:Ag/Ag were fabricated,using PVK:PBD:EuL₁L₂ as emitting layer,PBD as(exciton) block layer,and Alq₃ as electron transporting layer.The emission from electron transfer layer was easily seen because the lifetime of exicton of Eu complex.In the experiment,a electron transfer material PBD was used as exciton block layer.Alq₃ emission intensity become weaker than that of Eu complex,with the increase of the exciton block layer PBD thickness.As the block layer 80 nm,a pure red light with a peak of 612 nm and a half bandwidth of 10 nm,attribute to the(emission) of trivalent europium,was observed clearly.The assignment of the emission bands is referenced to(analogous) complex: 576 nm(⁵D₀→⁷F₀),590 nm(⁵D₀→⁷F₁),612 nm(⁵D₀→⁷F₂),652 nm(⁵D₀→⁷F₃),700 nm(⁵D₀→⁷F₄).The CIE coordinates of resulting emission was(0.608,0.339),a maximum luminescence brightness of 20cd/m² and external quantum efficiency brightness of 0.09% were achieved.