Synthesis and Properties of 9,9′-Diaryl-4,5-diazafluorenes. A New Type of Electron-Transporting and Hole-Blocking Material in EL Device

Abstract

The title compounds were prepared and investigated for electron-transporting and hole-blocking materials in organic electroluminescent (EL) devices. EL efficiencies of the phosphorescent devices indicated high performance of hole-blocking ability in the compounds. A maximum external efficiency of 18% was achieved and a maximum power luminous efficiency was over 45 Lm W−1.

Aluminium–salen luminophores as new hole-blocking materials for phosphorescent OLEDs

“…Hydrogen atoms are omitted for clarity. Selected bond lengths (A ˚) and angles ( • ): Al-O1 1.7900(17), Al-O2 1.7763(16), Al-O3 1.7609(16), Al-N1 1.9848(19), Al-N2 2.0093(19), O3-C33 1.339(3), O1-Al-O2 94.53(7), O1-Al-O3 97.33(8), O2-Al-O3 118.31(8), N1-Al-O1 89.26(8), N1-Al-O2 129.65(8), N1-Al-O3 110.86(8), N2-Al-O1 166.18(8), N2-Al-O2 88.18(7), N2-Al-O3 93.28(8), N2-Al-N1 78.66(8), C33-O3-Al 136.49(14).…”

9,9-Diaryl-4,5-diazafluorene-based Cardo polymer; Synthesis and characteristic properties

“…As the feed ratio of TsOH increased, the refractive indices ( n ) of the polymer decreased, probably because of the low refractive index of TsOH ( n 1.56 at 589 nm) and the decrease in the polymer density attributed to the introduction of ionic bonds with long distance between atoms. On the other hand, the birefringence value (Δ n ) also decreased along the increase of the feed ratio of TsOH, which would be attributed to the defect of ordered aggregation of polymer chain by the formation of hydrogen bonds and/or the existence of TsOH as a dorpant …”

“…To explore the useful derivatives of DAF ‐based polymers, we have previously reported the synthesis of modified cardo structure‐based polymers such as silafluorene‐type cardo polymer, sulfur‐containing polymers, 9,9′‐spirobifluorene‐based polymers, and their excellent properties such as higher thermal stability, higher refractive index, and lower birefringence than those of the corresponding DAF ‐containing polymers. We have recently focused our attention on the fusion of 4,5‐diazafluorene into a new cardo structure. Because the cardo polymer consisting of 4,5‐diazafluorene‐based cardo units ( N‐BPF ) has the regularly arranged nitrogens in the side chain, the applications of N‐BPF that use the characteristics of the nitrogen functionality seem interesting from new aspects of DAF ‐based polymers.…”

9,9-Bis(4-methoxyphenyl)-9H-cyclopenta[2,1-b:3,4-b′]dipyridine

“…The title compound, (I), was prepared and investigated for electron-transporting layers in the study of organic electroluminescent (EL) devices (Ono et al, 2004). Phosphorescent EL devices fabricated by (I) and Ir(ppy) 3 demonstrated high external quantum efficiencies due to the high hole-blocking ability of (I).…”