磷光染料/宽禁带半导体聚合物高效率能量转移体系的电致发光

Highly Efficient Energy Transfer System of Phosphorescence Dye/Board Band Gap Semiconductor Polymer

小分子磷光染料掺杂的聚合物发光器件具有发光效率高、制备工艺简单等优点,但是应该注意小分子染料的聚集与相分离问题,特别是在高掺杂浓度时更应注意防止相分离现象的发生。我们的思路是通过使用聚芴(Polyfluorene,PF)改性后的母体聚合物材料PC(poly[2,7-(9,9-dihexyl fluorene)-co-alt-2,10-(cyclohex-ane-1-spiro-6/-dibenzo[d,f][1,3]dioxepin)]),由于其发光峰位蓝移到紫外区,这就与作为掺杂分子的Ir(PPY)3配合物的吸收匹配得更好,进而达到提高能量转移效率的目的。在此条件下,可以实现较低掺杂浓度的发光,这对降低小分子染料的聚集以及相分离现象的发生是有帮助的。采用的器件结构为ITO/PEDOT:PSS/poly-mer:Ir(PPY)3/Ba/Al。当使用传统PF材料作为母体时,Ir(ppy)3需达到4％的掺杂比例才能实现能量的完全转移,而当采用改进后的PF作为母体时,Ir(ppy)3配合物只需达到0.5％的掺杂比例就能实现能量的完全转移,改进后的器件掺杂比例大幅度降低。

The devices of polymer mixed with phosphorescence dye have the virtue,of high efficient, easy to fabricate. But our attention should be given to the congregation and phase separation of the small molecule, especially at high concentration. By using a matrix polymer PC (poly[2, 7-(9, 9-dihexylfluorene)-co-alt-2, 10-(cyclohexane-l-spiro-6/-dibenzo [d, f][1,3] dioxepin)]), a kind of PF (polyflorene) polymers which have twist structure and have broad band gap causing the emission have a blue shift about 20nm than PF, more close to the absorption of Ir(ppy)3(iridium(Ⅲ) tri(2-phenylpyridinato-N, C2 )) , that means it can get a better matching between the emission of polymer and the absorption of phosphorescence dye, and achieve higher efficient energy transfer. At low concentration (about 0.5%), the matrix polymer PC can transfer its total energy to Ir(ppy)3. At such low concentration, congregation or phase separation can result less problem. The device structure is ITO/PEDOT∶PSS/polymer∶Ir(ppy)3/Ba/Al.