Blue Light-Emitting Diodes Based on Dipyrazolopyridine Derivatives

Abstract

A series of highly luminescent dipyrazolopyridine (PAP) dyes were synthesized and assessed as light-emitting materials in electroluminescent devices. Multilayer devices were fabricated using these dyes along with a hole-transporting material, NPB (4,4′-bis[N-(1naphthyl-1-)-N-phenyl-amino]-biphenyl) and an electron-transporting material, AlQ (tris-(8-hydroxyquinoline) aluminum), or TPBI (2,2′,2′′-(1,3,5-benzenetriyl)tris[1-phenyl-1Hbenzimidazole]). Both ITO/NPB/PAP/AlQ/Mg:Ag and ITO/NPB/PAP/TPBI/Mg:Ag devices gave a bright blue or blue-green emission, depending on the substituent group in the parent PAP dye. The performance of these devices such as turn-on voltage, brightness, and efficiency as a function of the substituent is discussed.

Progress in Modification of Indium-Tin Oxide/Organic Interfaces for Organic Light-Emitting Diodes

“…165 A green OLED with structure of ITO/MoO 3 /N, N -di(naphthalene-1-yl)-N,N -diphenyl-benzidene (NPB)/NPB Alq 3 :10-(2-benzothiazolyl)-2,3,6,7-tetrahydro-1,1,7,7-tetramethyl-1H, 5H, 11H-(1)-benzopyropyrano(6,7-8-i,j)quinolizin- 11-one (C545T)/Alq 3 /LiF/Al shows a long lifetime of over 50,000 h at 100 cd/m 2 initial luminance, and the power efficiency reaches 15 lm/W. The turn-on voltage is 2.4 V, and the operational voltage at 1,000 cd/m 2 luminance is only 6.9 V. The significant enhancement of performances is attributed to the improvement of hole injection and interface stability at anode.…”

“…[4][5][6][7][8][9][10][11][12][13] Nowadays, OLEDs including polymer and small-molecule LEDs are becoming increasingly important technology because of their potential applications for large flat-panel displays and general lighting owing to many advantages, such as faster switching speed, wider viewing angle, light weight, thinness, 14 potentially more power efficiency, better image quality, and lower cost. The basic concept of OLED is referred to in Veinot and Marks.…”

Synthesis and characterization of cyclometalated iridium(III) complexes containing pyrimidine-based ligands

“…Compounds Alq 3 (tris(8-hydroxyquinoline)aluminum) [32], CBP (4,4 0 -N,N 00 -dicarbazolebiphenyl) [33], and BPAPF (9,9-bis{4-{di(p-biphenyl)aminophenyl}}fluorene) [29] were synthesized according to literature procedures, and were sublimed twice prior to use. Prepatterned ITO substrates with an effective individual device area of 3.14 mm 2 were cleaned as described in a previous report [34]. A 40-nm-thick film of BPAPF was deposited first as the hole transport layer (HTL).…”

Efficient bifunctional materials based on pyrene- and triphenylamine-functionalized dendrimers for electroluminescent devices

“…Because of the large band gap energy, the performance of blue electroluminescent emitters is usually inferior to those of green and red emitters. Despite many blue electroluminescent systems, including fluorenes and spirofluorenes, 2 metal complexes, 3 oxadiazoles, 4 distyrylarylene derivatives, 5 pyrenes, 6 anthracenes, 7 aromatic amines, 8 and heterocyclic compounds, 9 have been synthesized and investigated, developing blue-emitters exhibiting not only with high efficiency but also with simple fabrication method remains a key challenge. Particularly, pyrene-based blue fluorescent emitters have attracted large attention for OLEDs, because the photoluminescence quantum yield, carrier mobility, and the electron-injection ability of emitters made of pyrene are higher when compared to those of fluorene derivatives.…”