稀土配合物与PVK共混体系发光特性及载流子复合区域转移的研究

Emitting Characteristics and Carrier Composite Regions Variety of the Blend of Terbium Complex and Poly-N-Vinylcarbazole

合成了一种新型的铽钆共掺稀土配合物TbGd(BA)6(bipy)2,把它作为发光材料应用于有机电致发光中。文中摸索了器件优化条件,并讨论了TbGd(BA)6(bipy)2与PVK共混体系的发光机理和载流子复合区域的转移。稀土配合物的光致发光是由于外部直接激发及PVK到稀土配合物的能量传递。电致发光有两个途径,PVK到稀土配合物的能量传递及载流子的直接俘获。在双层器件中,发光区域随Alq3厚度变化,尤其是在高电压下,载流子复合区域移向Alq3一侧,而在增加BCP作为空穴阻挡层的多层器件中,载流子限制在发光层和空穴阻挡层的界面处复合,随着电场的增强,铽发光趋于饱和,而出现了高分子基质的发光。优化后,得到213cd.m-2明亮的铽的绿色发光。

A new rare earth complex TbGd（BA）6 （bipy）2 was synthesized, which was used as an emitting material in electroluminescence. By doping with poly-N-vinylcarbazole（PVK）, the stability and conductivity of terbium complex were improved. The photolumineseenee of PVK, terbium complex and their blend indicated that energy transfer from PVK to terbium complex oc- curred. In the present paper, single-, double- and multi- layer devices were fabricated. In the double-layer devices, holes and e- lectrons were recombined at the interface of emitting layer （EML） and electron transporting layer （ETL）. With increasing the thickness of Alq3, especially at highly electric field, carrier composite region transferred closely to ETL. However, in multi-layer devices, carrier composite region was restricted at the interface of emitting layer and holes blocking layer （HBL） due to high HOMO level of BCP. Enhancing electric field, emission from terbium complex was getting saturation gradually and weak emis- sion from PVK was observed. From the optimized multi-layer device, bright and green emission from terbium complex was obtained with the highest EL brightness of the device of 213 cd · m^-2 at 13. 5 V.