一种新型金属铱(Ⅲ)类磷光材料的合成及性能研究

以邻氨基苯硫酚、苯甲酰氯为起始原料,通过与三氯化铱配合反应,合成了一种新型金属铱的(2-苯基苯并噻唑)配合物(bt)2Ir(acac),产率为45.47%,熔点为303～304℃.通过质谱、元素分析及红外光谱对其结构进行了表征,并对其光致发光性质进行了研究.研究表明,配合物在350～450nm存在单线态和三线态金属铱到配体的电荷跃迁,在566.0 nm处有强的金属配合物三线态磷光发射,配合物(bt)2Ir(acac)是一种新型的磷光材料.     

一种新型绿色磷光材料合成及性能研究

以邻苯二胺和苯甲醛为原料,通过与三氯化铱配合,制得一种新型绿色磷光铱(Ⅲ)1-苯甲基-2-苯基苯并咪唑(bpbi)乙酰丙酮(acac)配合物(bpbi)_2Ir(acac)。通过质谱、核磁对其结构进行了表征,并对其光致发光性能进行了研究。研究结果表明:(bpbi)_2Ir(acac)在411和454nm处的可见光吸收属于单线态和三线态金属铱到配体的电荷越迁;在515nm处有强的绿色磷光发射;(bpbi)_2Ir(acac)的最高占据轨道(HOMO)为-4.59eV、最低空轨道(LUMO)为-1.01eV。(bpbi)_2Ir(acac)是一种极有潜力的电致磷光材料。     

短寿命铱(Ⅲ)配合物在有机电致发光(OLED)中的应用

设计并合成了两种有机电致发光材料,Ir(ppi)2acac和Ir(MeO-ppi)2acac,其中ppi和MeO-ppi分别为2-苯基苯并咪唑和2-(4′-甲氧基苯基)苯并咪唑,acac=乙酰丙酮,Ir(ppi)2acac和Ir(MeO-ppi)2ac,Ir(Ⅲ)配合物在二氯甲烷溶液中的磷光寿命(τ)分别为52.0和43.6ns,在CBP 薄膜中的τ分别为3.7和3.3ns,如此短的三重态寿命目前尚未看到报道.研究发现高效的Ir(ppi)2acac的绿电光致发光(EL)性能与短三重态寿命密切相关,7%(质量分数)Ir(ppi)2acac掺杂的器件给出55060cd/m2的最高亮度(L),对应13.4% 最大外量子效率(η),比Ir(ppy)3掺杂的参考器件提高了67.5%.     

新型铱配合物[Ir(dmpq)_2(Br_2bpy)]~+PF~-_6的合成、晶体结构及光物理性能测试

以喹啉类化合物为环金属配体,4,4′-二溴-2,2′-联吡啶为辅助配体成功合成出了一种新型离子型环金属铱配合物:[Ir(dmpq)_2(Br_2bpy)]~+PF~-_6(dmpq=2-(3,5-二甲苯基)喹啉,Br_2bpy=4,4′-二溴-2,2′-联吡啶)。配合物的结构通过元素分析、核磁共振谱、红外光谱、质谱进行了表征,并测试了单晶结构。并通过紫外-可见吸收、荧光光谱,对配合物的激发态进行了讨论,同时考察了配合物的热稳定性。结果表明配合物为单斜晶系、空间群为P2_1/n;配合物在溶液状态下为红光发射,最大发射波长为649 nm。     

高效磷光红光配合物Ir(pq)_2(acac)的合成、结构表征及光物理性能测试

以2-氯喹啉和苯硼酸为原料,在四(三苯基膦)钯作催化剂下反应得到主配体2-苯基喹啉(pq),之后pq与水合三氯化铱在乙二醇单乙醚溶剂中反应得到铱的氯桥二聚体(pq)_2Ir(μ-Cl_2)Ir(pq)_2,然后在碱性条件下和乙酰丙酮反应合成出高效磷光红光材料二(2-苯基喹啉-C2,N')(乙酰丙酮)合铱(Ⅲ)Ir(pq)_2(acac)。通过元素分析、红外光谱、核磁共振谱(~1 H NMR、~(13)C NMR)、质谱和单晶X射线衍射等表征手段确定了分子结构,利用紫外-可见吸收光谱和光致发光光谱对其光物理性能进行了测试。结果表明,Ir(pq)_2(acac)为电中性八面体配合物,Ir—O键的平均长度为0.21741(18)nm,而Ir—C键的平均长度0.1983(3)nm,Ir—N键的平均长度为0.2079(2)nm,在600nm处出现了较强的红光发射,其合成产率95%,该方法适于Ir(pq)_2(acac)的小批量制备。     

新型含铱共聚物的合成及表征

利用2-对甲苯基吡啶(ptpy)、对乙烯基苯甲酸(VBA)和三水合氯化铱(IrCl_3·H_2O)配位,得到了铱配合物单体Ir(ptpy)_2(VBA),再将其与乙烯基咔唑共聚制得了一种含铱配合物的新型聚合物.通过元素分析、FT-IR光谱和~1H NMR谱等对Ir(ptpy)-2(VBA)和聚合物的结构进行了表征.凝胶色谱仪(GPC)测试结果表明,聚合物的数均分子量(Mn)为8230.此外还研究了Ir(ptpy)_2(VBA)和聚合物的紫外-可见(UV-vis)吸收光谱和光致发光(PL)光谱.光致发光光谱测试结果表明,聚合物在固态时,主体咔唑基团向客体铱配合物基团有着较为有效的能量转移.聚合物在501nm处有较强的金属配合物三重态的磷光发射峰,是一种绿色磷光材料.     

树枝状铱配合物的合成与发光性能研究

设计、合成了3个新颖的环金属配体1-苯甲基-2-苯基-苯并咪唑[BPBM]、1-(4-甲氧基-苯甲基)-2-(4-甲氧基-苯基)-苯并咪唑[MBMPB]和1-(4-N,N-二甲基-苯甲基)-2-(4-N,N-二甲基-苯基)-苯并咪唑[DBPA],并以乙酰丙酮(Hacac)为辅助配体合成了3个高效绿色铱配合物Ir(BPBM)2(acac)(1)、Ir(MBMPB)2(acac)(2)和Ir(DPBA)2(acac)(3)。由于在配体上引入了大的非平面取代基,分子间的浓度猝灭被有效地抑制;室温下,3个配合物在纯固态下都展示了明亮的绿光发射,且详细研究了它们的热稳定性和光物理性能。结果表明:该类配合物具有短的激发态寿命和高的光致磷光效率,在制备非掺杂有机电致发光器件方面具有潜在的应用前景。     

有机小分子电致磷光材料研究进展

在过去20年对小分子电致发光器件的研究中,由于没有充分利用三线态激子能量,器件的内量子效率存在25%的理论极限.由于有机磷光染料可以同时利用其单线态和三线态激子,理论上可以使器件的内量子效率达到100%,突破了25%的理论极限,因而近几年在小分子主体材料中掺杂磷光染料制成器件的研究备受关注.综述了近几年金属有机电致磷光材料的研究进展,重点评述了金属铱配合物在分子设计上的研究进展,同时论述了其发光机理和掺杂剂材料以及器件制作的研究进展,展望了金属有机配合物电致磷光材料的发展前景,并提出了今后磷光材料的发展方向.     

2-(2-羟基苯基)苯并噻唑-十一烯酸-锌与苯乙烯共聚物制备及性能研究

采用先配合再聚合的技术路线,先以Zn2+为中心离子,2-(2-羟基苯基)苯并噻唑为第一配体、10-十一烯酸为活性配体合成了反应型锌配合物2-(2-羟基苯基)苯并噻唑-十一烯酸-锌[Zn(BTZ)(UA)];再采用溶液聚合法,将Zn(BTZ)(UA)与苯乙烯共聚制备了聚苯乙烯-2-(2-羟基苯基)苯并噻唑-十一烯酸-锌[St-co-Zn(BTZ)(UA)]。通过红外光谱、紫外光谱、荧光光谱和热重分析对配合物和聚合物的结构和发光性能进行了表征。红外和紫外光谱表明,共聚物不仅表现出了聚苯乙烯的吸收,也表现出了配合物的吸收;荧光光谱表明,配合物在395nm的激发波长下发射蓝绿光,发射峰位于471nm处;聚合物在395nm的激发波长下,发射蓝光,发射峰位于451nm处,色坐标为(0.145,0.139),位于蓝光区;热重分析显示,聚合物的热分解温度为273℃,可用于三基色白光LED荧光粉的蓝光成分。     

1,2,4-噁二唑类双极性磷光主体材料的合成及性质

设计合成了两种以1,2,4-噁二唑受体基团为核心且具有D-A结构的双极性磷光主体材料:3,5-二(3-(9-吩噻嗪基)苯基)-1,2,4-噁二唑(MMOXD)和3,5-二(4-(9-吩噻嗪基)苯基)-1,2,4-噁二唑(PPOXD)。在表征其结构的基础上,对其光谱学、电化学和热力学性质进行了研究。结果显示,MMOXD和PPOXD的荧光发射峰分别为388、465和377、448 nm。测定其低温磷光光谱可得它们的三线态能级为2.93和2.46 eV,可分别与深蓝色、蓝色磷光客体材料(如FCNIrpic(2.74 eV)、FIrpic(2.65 eV))和绿色磷光客体材料(如Ir(ppy)_3(2.40 eV))相匹配。利用循环伏安法测定其最高占有分子轨道(HOMO)能级分别为-5.88和-5.25 eV,接近于阳极ITO玻璃的功函(-4.5～-5.0 eV),最低未占分子轨道(LUMO)能级分别是-2.29和-2.32 eV,接近于电子传输材料TPBi的功函(-2.70 eV),且他们的轨道电子云均明显分离,表明其具有良好的双极性质。TGA和DSC测试可知它们在质量损失为5%时的热分解温度(394,275℃)和玻璃化转化温度(181,170℃)均较高,表明这两种材料具有优异的热稳定性和成膜性。综上所述,PPOXD有用作双极性绿色磷光主体材料的潜力,而MMOXD有用作双极性深蓝色或蓝色磷光主体材料的潜力。     

Synthesis and photo physical study of iridium complex of new pentafluorophenyl-substituted ligands

New iridium complexes, [Ir(dpq)₂(acac), Ir(PF-dpq)₂(acac) and Ir(PF-dpq-5F)₂(acac)] (dpq = 2,4-diphenylquinoline, dpq-5F = 2-(3′-fluorophenyl)-4-phenylquinoline), PF-dpq-5F = 2-(3-fluoro-phenyl)-6-pentafluorophenyl-4-phenylquinoline and acac = acetylacetonate) have been synthesized and characterized for efficient red organic light-emitting diodes (OLEDs). In order to improve the luminescence efficiency by preventing self-quenching and to tune photoluminescence (PL) and electroluminescence (EL) spectra to a longer wavelength, dpq ligand was fluorinated by -PF and -F moieties. However, the iridium complex of PF-dpq-5F underwent a weak MLCT transition because of the weak coupling between the 5d orbital of the iridium atom and HOMO of the substituted ligand. Thus, the maximum luminous efficiencies of the device using Ir(dpq)2(acac), Ir(PF-dpq)₂(acac) and Ir(PF-dpq-5F)₂(acac) are 4.36 cd/A, 6.04 cd/A and 4.35 cd/A, respectively.     

The new iridium complexes involving pyridylpyridine derivatives for the saturated blue emission

To obtain a saturated blue phosphorescent material with a good color purity, we have synthesized the new blue emitting iridium complexes with 2, 6-difluoro-3-(4-methylpyridin-2-yl)pyridine (4-Me-dfpypy) as a main ligand. We expected that the LUMO energy levels of the complex might increase upon introduction of an electron donating group such as a methyl group to the pyridyl moieties of the ligand, leading to a wide energy gap of the complex to give the saturated blue emission. We have also introduced a variety of the ancillary ligands to the iridium center to compare the effect of the ancillary ligards on the emission of their complexes. The resulting iridium complexes, Ir(4-Me-dfpypy)3, Ir(4-Me-dfpypy)2(acac), Ir(4-Me-dfpypy)2(pic) and Ir(4-Me-dfpypy)2(trzl-CH3) where acac, pic, and trzl-CH3 represent acetylacetonate, picolinate, and 2-(5-methyl-2H-1,2,4-triazol-3-yl) pyridinate, respectively exhibited the blue emission at 451, 447, 440 and 425 nm in CH2Cl2 solution. The organic light emitting device (OLED) employing homoleptic Ir(4-Me-dfpypy), as the blue dopant was prepared and their electroluminescence was investigated. Ir(4-Me-dfpypy)3 exhibited the blue emission of CIE coordinates (0.22, 0.32).     

Theoretical study of iridium complexes with phenylpyridine based ligands and phosphines

Recently, iridium complexes with phenylpyridine based ligands and phosphines, Ir(C(see text for symbol)N)2 (PPh3)(CN), [(C(see text for symbol)N) = dfppy, dfMeppy] are reported as blue phosphorescent OLED materials. These iridium complexes have novel blue color and emit light at 441 nm to 439 nm. However, these complexes have low external quantum efficiency because they exhibit less MLCT than iridium complexes with phenylpyridine, and some other ancillary ligands. To improve quantum efficiency of iridium complexes with phenylpyridine based ligands and phosphines, a time dependent density functional theory (TDDFT) study of these phosphors was performed. Using these results, this paper discusses how the ancillary ligand influences the emission peak, as well as the metal to ligand charge transfer (MLCT) transition efficiency.     

Efficient phosphorescent white organic light-emitting diodes using Ir(4-Me-2,3-dpq)2(przl-C6H4F) as a red emitter

We demonstrated white organic light-emitting diodes (WOLED) using the iridium bis(4-methyl-2,3-phenylquinolinato-N,C2) fluorophenylpyrazolonate complex (Ir(4-Me-2,3-dpq)2(przl-C6H4F)) as a phosphorescent red dopant and iridium bis[(4,6-difluorophenyl)-pyridinato-N,C2] picolinate (Flrpic) as a phosphorescent blue dopant. The WOLED with Ir(4-Me-2,3-dpq)2(przl-C6H4F) had better exciton confinement in emitting layer and indicated smaller movement of exciton than the WOLED with iridium bis(2-phenylquinoline) acetylacetonate (Ir(2-pq)2(acac)) as phosphorescent red dopant. The optimized WOLED had a peak external quantum efficiency of 7.16%, current efficiency of 11.84 cd/A, and Commission Internationale de l'Eclairage (CIE(x,y)) coordinates of (0.35, 0.32). The WOLED also exhibited the minimal change with delta CIE(x,y) coordinates of +/- (0.01, 0.00) from 100 to 4000 cd/m2.     

Efficient triplet exciton confinement of blue- and white-organic light emitting diodes using a new host material

We have demonstrated lower driving voltage and efficient blue phosphorescent organic light emitting diodes (PHOLEDs) using iridium(III) bis[(4,6-di-fluoropheny)-pyridinato-N,C2] picolinate (Flrpic) doped in new host material 9-(4-(triphenylsilyl)phenyl)-9H-carbazole (SPC) and 2,2',2"-(1,3,5-benzenetryl)tris(1-phenyl)-1H-benzimidazol (TPBi) as double-emitting layer (D-EML) system. The D-EML was employed to have good electron transportability and exciton confinement. Additionally, we fabricated white organic light-emitting diode (WOLED) using a phosphorescent red emitter; bis(2-phenylquinolinato)-acetylacetonate iridium III (Ir(pq)2acac) doped in SPC and TPBi as D-EML. The properties of white device exhibited a maximum luminous efficiency of 19.03 cd/A, a maximum external quantum efficiency of 9.91%, and a maximum power efficiency of 12.30 lm/W. It also showed white emission with CIE(x,y) coordinates of (x = 0.38, y = 0.37) at 8 V.     

Synthesis and luminescence of a new phosphorescent iridium(III) pyrazine complex

The synthesis and luminescent study of a new iridium pyrazine complex are reported. The iridium complex [Ir(MDPP)2(acac)] (MDPP=5-methyl-2,3-diphenylpyrazine, acac=acetylacetone) shows strong ¹MLCT (singlet metal-to-ligand charge-transfer) and ³MLCT (triplet metal to ligand charge-transfer) absorption at 386 and 507 nm, respectively. Organic light emitting device (OLED) with a configuration of ITO / NPB (30 nm) / NPB: 7% (wt.) Ir(MDPP)₂(acac) (25 nm) / BCP (10 nm) / Alq₃(30 nm) / Mg : Ag (mass ratio 10 : 1)120 nm / Ag(10 nm) exhibits an external quantum efficiency of 6.02% (power efficiency 9.89 lm W^− 1 ) and a maximum brightness of 78,924 cd m^− 2. The device also shows high color purity with a maximum peak at 576 nm without any shoulder.     

Efficient red-emitting phosphorescent iridium(III) complexes of fluorinated 2,4-diphenylquinolines

Ir(β) complexes of fluorinated dpqs(dpq-3-F, dpq-4-CF₃) as a cyclometallated ligand were prepared and their photonic properties were investigated, where dpq-3-F and dpq-4-CF₃ represent 2-(3-fluoro-phenyl)-4-phenylquinoline and 4-phenyl-2-(4-trifluoromethylphenyl)quinoline, respectively. Fluorinated dpq derivatives were introduced to the iridium complexes to increase the efficiency compared to Ir(dpq)₂(acac) which was recently reported to have emission wavelength of 614 nm with quantum efficiency of 0.14. These fluorinated ligands and their Ir(III) complexes were computationally calculated by ab initio methods to support our experimental results. It was found that the Ir complex containing dpq-3-F ligands exhibits the largest emission efficiency with maximum emission peak at 593.5 nm. The result of ab initio calculation using the time-dependent density functional theory (TD-DFT) showed that the strong ³MLCT transition of the complex occurs due to the strong coupling between the 5d orbital of the Ir atom and the highest occupied molecular orbitals (HOMOs) of these ligands.     

Study on energy relation between blue and red emissive layer of organic light-emitting diodes by inserting spacer layer

In this paper, energy relation between blue emissive layer (blue-EML) and red emissive layer (red-EML) in organic light-emitting diodes based on blue-emitting and red-emitting phosphorescent dopants, bis(3,5-difluoro-2-(2-pyridyl)phenyl-(2-carboxypyridyl) iridium III (Firpic) and bis(2-(2′-benzo[4,5-α]thienyl)pyridinato-N,C3′)iridium(acetylacetonate) (Btp₂Ir(acac)), was studied. Two phosphorescent dopants, Firpic and Btp₂Ir(acac), were co-doped in the single emissive layer, and the results exhibit complete energy transfer from Firpic to Btp₂Ir(acac). Then, Firpic and Btp₂Ir(acac) were doped into blue-EML and red-EML, separately. By inserting 4,4′-bis(N-carbazolyl)biphenyl (CBP) spacer between blue- and red-EML, energy relation between blue- and red-EML was researched. The results of this work reveal that, CBP spacer may strengthen energy transfer between blue- and red-EML. The reason is that CBP triplets at blue-/red-EML interface can transfer their energies to both CBP molecules of red-EML and Firpic molecules of blue-EML in spacer-without devices, while CBP triplets in the spacer can transfer their energies only to CBP molecules of red-EML. Therefore, energy flow from blue- to red-EML is strengthened because of the avoidance of energy transfer from CBP triplets in the spacer to Firpic molecules of blue-EML, leading to the relative enhancement of red emission in CBP-spacer devices.     

High-efficiency white organic light-emitting devices with a non-doped yellow phosphorescent emissive layer

Highly efficient phosphorescent white organic light-emitting devices (PHWOLEDs) with a simple structure of ITO/TAPC (40 nm)/mCP:FIrpic (20 nm, x wt.%)/bis[2-(4-tertbutylphenyl)benzothiazolato-N,C²′] iridium (acetylacetonate) (tbt)₂Ir(acac) (y nm)/Bphen (30 nm)/Mg:Ag (200 nm) have been developed, by inserting a thin layer of non-doped yellow phosphorescent (tbt)₂Ir(acac) between doped blue emitting layer (EML) and electron transporting layer. By changing the doping concentration of the blue EML and the thickness of the non-doped yellow EML, a PHWOLED comprised of higher blue doping concentration and thinner yellow EML achieves a high current efficiency of 31.7 cd/A and Commission Internationale de l'Eclairage coordinates of (0.33, 0.41) at a luminance of 3000 cd/m² could be observed.     

High efficiency red organic light-emitting diodes using a phosphorescent iridium complex doped into a hole-blocking material

We demonstrate high-efficiency red electrophosphorescent organic light-emitting devices (OLEDs) by doping a red-emitting iridium complex, Bis[7-methyl-1-p- tolyisoquinolinato-N,C²′]-iridium(III)(acetylacetonate) [(7-mtiq)₂Ir(acac)], into a hole-blocking material, 4-biphenyloxolato aluminum(III)bis(2-methyl-8- quinolinato)4-phenylphenolate. Both the phosphorescent characteristics of (7-mtiq)₂Ir(acac) and the electroluminescence mechanisms of OLEDs are investigated in this study. The Commission Internationale de L'Eclairage coordinates of (0.66, 0.34) is very close to the National Television System Committee standard red point (0.66, 0.33). With a dopant concentration of about 4%, a maximum luminance of 31317 cd/m² and a luminous efficiency of 21.6 cd/A have been obtained.