Blue emitting iridium complexes: synthesis, photophysics and phosphorescent devices
作者:Roberta Ragni、Edward A. Plummer、Klemens Brunner、Johannes W. Hofstraat、Francesco Babudri、Gianluca M. Farinola、Francesco Naso、Luisa De Cola
DOI:10.1039/b512081k
日期:——
Homoleptic Ir(Fnppy)3 and heteroleptic (Fnppy)2Ir(acac) complexes (n = 3: F3ppy = 2-(3′,4′,6′-trifluorophenyl)pyridine; n = 4: F4ppy = 2-(3′,4′,5′,6′-tetrafluorophenyl)pyridine; acac = acetylacetonate) have been synthesized and their spectroscopic properties investigated. The homoleptic complexes exist as two stereoisomers, facial (fac) and meridional (mer), that have been isolated and fully characterized. Their electrochemical and photophysical properties have been studied both in solution and in the solid state and electroluminescent devices have been fabricated. The emissive layers in devices have been obtained mixing the iridium complexes with a PVK [poly(9-vinylcarbazole)] host matrix, in the presence of the electron carrier Bu-PBD [2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole]. The application of a voltage (5.0–6.5 V) between the electrodes of devices leads to electro-generated blue luminescence which has similar energy to the solution emissions. Interestingly, the stability of the devices made with the homoleptic fluorinated iridium complexes strongly depends on the stereochemistry of these phosphors and high (up to 5.5%) external quantum efficiencies for the fac complexes are measured.
合配体Ir(Fnppy)3和异配体(Fnppy)2Ir(acac)复合物(n = 3: F3ppy = 2-(3′,4′,6′-三氟苯基)吡啶;n = 4: F4ppy = 2-(3′,4′,5′,6′-四氟苯基)吡啶;acac = 乙酰乙酸盐)已被合成,并对其光谱性质进行了研究。合配体复合物存在两种立体异构体:面心型(fac)和经度型(mer),这些异构体已被分离并完全表征。它们的电化学和光物理性质在溶液和固态中均进行了研究,并制造了电致发光器件。器件中的发光层是通过将铱复合物与PVK [聚(9-乙基咔唑)]宿主基质混合获得的,并加入电子载体Bu-PBD [2-(4-联苯基)-5-(4-叔丁基苯基)-1,3,4-噁二唑]。在器件电极之间施加电压(5.0-6.5 V)会产生电致蓝光发射,其能量与溶液发射相似。有趣的是,使用合配体氟化铱复合物制成的器件的稳定性强烈依赖于这些磷光体的立体化学,而fac复合物的外量子效率高达5.5%。