Emission Characteristics of PVK Doped TbY(o-MBA)6(phen)2 Systems

A rare earth complex TbY (o-MBA)6(phen)2 was synthesized, which was first used as an emitting material in electroluminescence. By doping it into the conjugated polymer PVK, single-layer and double-layer devices were fabricated with structures: device A: ITO/PVK: TbY (o-MBA)6(phen)2/BCP/Al; B: ITO/PVK: TbY (o-MBA)6(phen)2/AlQ/LiF/Al; C: ITO/PVK: TbY (o-MBA)6(phen)2/BCP/AlQ/LiF/Al. The characteristics of these devices were investigated. For single-layer and double-layer devices, the emission of PVK was completely restrained, and only the green emission from Tb3+ was observed in electroluminescence. The above mentioned observation is attributed to the different mechanism of electroluminescence and photoluminescence. In photoluminescence process, the energy of Tb complex may come from PVK through Förster energy transfer process, while in electroluminescence process direct sequential charge trapping appeares to be the main operating mechanism. From the optimized device B, brightly green emission can be obtained, and the highest EL brightness of the device reaches 213 cd·m−2 at 14 V.