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Photo- and electroluminescent properties europium complexes using bistriazole ligands.

Gusev AN, Shul'gin VF, Nishimenko G, Hasegawa M, Linert W - Synth Met (2013)

Bottom Line: Luminescent properties of two heteroleptic dibenzoylmethanate europium(III) complexes with 1,3-bis(5-pyridin-2-yl-1,2,4-triazol-3-yl)propane (H2L(1)) and 1,4-bis(5-pyridin-2-yl-1,2,4-triazol-3-yl)butane (H2L(2)) as ancillary ligands are described.The two double-layer-type electroluminescent cells with the structures: (1) ITO/NPB(40 nm)/Eu(DBM)2HL(1) (40 nm)/LiF (1 nm)/Al (100 nm) and (2) ITO/NPB(40 nm)/Eu(DBM)2HL(2) (40 nm)/LiF (1 nm)/Al (100 nm) emit red light originating from the europium complexes.The device 2 gives the maximum brightness of 455 cd/m(2) at 19.2 V.

View Article: PubMed Central - PubMed

Affiliation: Taurida National V.I. Vernadsky University, Simferopol 95007, Ukraine.

ABSTRACT
Luminescent properties of two heteroleptic dibenzoylmethanate europium(III) complexes with 1,3-bis(5-pyridin-2-yl-1,2,4-triazol-3-yl)propane (H2L(1)) and 1,4-bis(5-pyridin-2-yl-1,2,4-triazol-3-yl)butane (H2L(2)) as ancillary ligands are described. The two double-layer-type electroluminescent cells with the structures: (1) ITO/NPB(40 nm)/Eu(DBM)2HL(1) (40 nm)/LiF (1 nm)/Al (100 nm) and (2) ITO/NPB(40 nm)/Eu(DBM)2HL(2) (40 nm)/LiF (1 nm)/Al (100 nm) emit red light originating from the europium complexes. The device 2 gives the maximum brightness of 455 cd/m(2) at 19.2 V.

No MeSH data available.


Drawing of the bis(pyridyltriazolyl)alkanes and Eu complexes.
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fig0010: Drawing of the bis(pyridyltriazolyl)alkanes and Eu complexes.

Mentions: The search for new materials for organic light-emitting diodes (OLEDs) is one of the actual problems of both chemistry and materials science [1–3]. Despite the significant progress achieved in this field for the last decade, the production of brightness luminescent materials that can be used as active layers in OLEDs remains important. There are three main classes of luminophore that are most suitable for producing of electroluminescent devices: rigid organic molecules, d-metals complexes, and lanthanide complexes [1,4–6]. Until now first two classes are more popular as electroluminophore due to very high quantum efficiency of luminescence, high chemical stability and electronic conductivity. However, despite all the advantages, obtaining the luminescence spectrum with a small half-width at half-maximum remains an open issue for the phosphor of this type. In contrast lanthanide complexes with organic ligands can provide potential solutions for such issue due to the central lanthanide metal ions exhibit extremely sharp emission bands as results of their specific electronic structure. Unfortunately till now the most efficient Ln(III) phosphors doesn’t show high electroefficiency. One of the important reasons is the poor carrier transporting properties (especially electron-transporting) of these complexes [7]. Unbalanced injection and transport of charge carriers would cause their recombination at locations other than the emitting layer, leading to low OLEDs efficiency and reduced lifetime. There are two main approaches to improve carrier-transporting properties of the europium complexes. The first is doping europium complexes into polymers or small molecular compounds with high hole or electron mobility. The second one is grafting hole- or electron-transporting units on ligands. It is well known that 1,3,4-oxadiazole and 1,2,4-triazole derivatives are the most widely employed as electron-transporting and hole-blocking materials [8]. Several groups have been focused on the design and synthesis of oxadiazole-functionalized β-diketonate ligands and corresponding lanthanide complexes. The literature contains several interesting results which show the effectiveness of such direction of investigation for improving carrier transporting properties of Eu(III) complexes [9–11]. However, we could not find any mention about employing triazole derivatives as ligands for design luminescent europium complexes. Recently we reported about new pyridyltriazole ancillary ligands which effectively enhance photoluminescence of Eu(III) with respect to Eu(DBM)3·2H2O (HDBM – dibenzoylmethane) [12]. Here we give detailed description of photo- and electroluminescent properties of europium complexes based on bis(pyridyltriazolyl)alkanes and DBM− presented in Fig. 1.


Photo- and electroluminescent properties europium complexes using bistriazole ligands.

Gusev AN, Shul'gin VF, Nishimenko G, Hasegawa M, Linert W - Synth Met (2013)

Drawing of the bis(pyridyltriazolyl)alkanes and Eu complexes.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3584924&req=5

fig0010: Drawing of the bis(pyridyltriazolyl)alkanes and Eu complexes.
Mentions: The search for new materials for organic light-emitting diodes (OLEDs) is one of the actual problems of both chemistry and materials science [1–3]. Despite the significant progress achieved in this field for the last decade, the production of brightness luminescent materials that can be used as active layers in OLEDs remains important. There are three main classes of luminophore that are most suitable for producing of electroluminescent devices: rigid organic molecules, d-metals complexes, and lanthanide complexes [1,4–6]. Until now first two classes are more popular as electroluminophore due to very high quantum efficiency of luminescence, high chemical stability and electronic conductivity. However, despite all the advantages, obtaining the luminescence spectrum with a small half-width at half-maximum remains an open issue for the phosphor of this type. In contrast lanthanide complexes with organic ligands can provide potential solutions for such issue due to the central lanthanide metal ions exhibit extremely sharp emission bands as results of their specific electronic structure. Unfortunately till now the most efficient Ln(III) phosphors doesn’t show high electroefficiency. One of the important reasons is the poor carrier transporting properties (especially electron-transporting) of these complexes [7]. Unbalanced injection and transport of charge carriers would cause their recombination at locations other than the emitting layer, leading to low OLEDs efficiency and reduced lifetime. There are two main approaches to improve carrier-transporting properties of the europium complexes. The first is doping europium complexes into polymers or small molecular compounds with high hole or electron mobility. The second one is grafting hole- or electron-transporting units on ligands. It is well known that 1,3,4-oxadiazole and 1,2,4-triazole derivatives are the most widely employed as electron-transporting and hole-blocking materials [8]. Several groups have been focused on the design and synthesis of oxadiazole-functionalized β-diketonate ligands and corresponding lanthanide complexes. The literature contains several interesting results which show the effectiveness of such direction of investigation for improving carrier transporting properties of Eu(III) complexes [9–11]. However, we could not find any mention about employing triazole derivatives as ligands for design luminescent europium complexes. Recently we reported about new pyridyltriazole ancillary ligands which effectively enhance photoluminescence of Eu(III) with respect to Eu(DBM)3·2H2O (HDBM – dibenzoylmethane) [12]. Here we give detailed description of photo- and electroluminescent properties of europium complexes based on bis(pyridyltriazolyl)alkanes and DBM− presented in Fig. 1.

Bottom Line: Luminescent properties of two heteroleptic dibenzoylmethanate europium(III) complexes with 1,3-bis(5-pyridin-2-yl-1,2,4-triazol-3-yl)propane (H2L(1)) and 1,4-bis(5-pyridin-2-yl-1,2,4-triazol-3-yl)butane (H2L(2)) as ancillary ligands are described.The two double-layer-type electroluminescent cells with the structures: (1) ITO/NPB(40 nm)/Eu(DBM)2HL(1) (40 nm)/LiF (1 nm)/Al (100 nm) and (2) ITO/NPB(40 nm)/Eu(DBM)2HL(2) (40 nm)/LiF (1 nm)/Al (100 nm) emit red light originating from the europium complexes.The device 2 gives the maximum brightness of 455 cd/m(2) at 19.2 V.

View Article: PubMed Central - PubMed

Affiliation: Taurida National V.I. Vernadsky University, Simferopol 95007, Ukraine.

ABSTRACT
Luminescent properties of two heteroleptic dibenzoylmethanate europium(III) complexes with 1,3-bis(5-pyridin-2-yl-1,2,4-triazol-3-yl)propane (H2L(1)) and 1,4-bis(5-pyridin-2-yl-1,2,4-triazol-3-yl)butane (H2L(2)) as ancillary ligands are described. The two double-layer-type electroluminescent cells with the structures: (1) ITO/NPB(40 nm)/Eu(DBM)2HL(1) (40 nm)/LiF (1 nm)/Al (100 nm) and (2) ITO/NPB(40 nm)/Eu(DBM)2HL(2) (40 nm)/LiF (1 nm)/Al (100 nm) emit red light originating from the europium complexes. The device 2 gives the maximum brightness of 455 cd/m(2) at 19.2 V.

No MeSH data available.