8-羟基喹啉铝在多孔铝中的发光研究

Photoluminescence Spectra of 8-hydroxyquinoline Aluminum Embedded in Porous Alumina

利用多孔铝非常高的孔隙率,将8-羟基喹啉铝(Alq3)镶嵌到多孔铝中,得到Alq3/多孔铝镶嵌膜,研究了不同条件下制备的多孔铝镶嵌膜的荧光光谱。实验表明,Alq3在多孔铝中的发光峰位在490 nm左右,比其在固态粉末状态蓝移了许多。Alq3/多孔铝镶嵌膜的发光特性与多孔铝中嵌入Alq3分子的数量及聚集程度有关。当分子数量较多、聚集程度较大时,发光增强,光谱峰位红移,但聚集程度太大时,易发生荧光猝灭现象。数量较多时,由于Alq3分子大多以范德瓦尔斯力结合,聚体较少,所以峰位移动幅度不大。实验中还发现,Alq3因为处在小孔中,光学性质稳定,荧光光谱带宽超过100 nm,比一般染料大得多,这使Alq3/多孔铝镶嵌膜有可能在固体可调谐激光器方面得到新的应用;同时也为探究Alq3/多孔铝镶嵌膜在电致发光器件中的发光特性奠定了基础,为将其进一步推向实用提供了实验依据。

Alq(3) is the key electroluminescent material currently used in organic light-emitting devices (OLEDs) based on 'small molecules '. In the study of OLEDs Alq(3) was used as the active layer, and significant fluorescent degradation of Alq(3) was found in a room ambient. In order to extend the periods of time of OLEDs, at the present time, researchers try to encapsulate it in special environments with cooling equipment, thus to make the capacity larger and the cost higher. As the optical properties of anodic alumina is good, and the pore of anodic alumina is much larger than the molecular diameter of Alq(3), Alq(3) can be successfully embedded in the porous alumina. To clarify the optical properties of the embedded films, we have done a series of experiments to study the photoluminescence(PL) of the embedded films. It was shown that the peak of PL of the compound film was at about 490 nm, blue shifted a lot compared with that of the solid matter, and the PL was correlative with the quantity and the degree of conglomeration of the molecule of Alq(3) embedded in the porous alumina. With the number increasing, the peak of PL exhibited a red shift, and the intensity enhanced; but the intensity decreased unexpectedly when the conglomeration was too large. As most of the molecules of Alq(3) existed in Van der Waals binding when the number was high, the peak shifted a little. The broad full width at half maximum(FWHM) of the PL and the stability of Alq(3) in the porous alumina may make the embedded film a new application in the tunable solid laser. At the same time, for the similarity in the mechanism of PL and EL, the experimental results suggest the properties of embedded film in EL devices and provide a base for application in electroluminescence.