Fluorene‐Carbazole Dendrimers: Synthesis, Thermal, Photophysical and Electroluminescent Device Properties

Abstract

Novel hole‐transporting dendrimeric molecules containing dioctylfluorene, spirobi(fluorene) and spiro(cylododecane‐fluorene) as the core unit and different numbers of carbazole and thiophene moieties as the peripheral groups are synthesized. All the dendrimers are characterized by 1H NMR, 13C NMR, FTIR, UV–vis, PL spectroscopy, and MALDI‐TOF. They are thermally stable with high glass transition and decomposition temperatures and exhibit chemically reversible redox processes. They are used as the hole‐transporting layer (HTL) material for multilayer organic light emitting diodes (OLEDs) with a low turn‐on voltage of around 2.5 V and a bright green emission with a maximum luminance of around 25400 cd m−2.

Electroluminescence performance of a series of fluorene/2,5‐di(2‐thienyl)‐1H‐pyrrole polymers

“…9 Fluorene derivatives have various advantages for OLED application because of their high electroluminescence (EL) efficiencies, high quantum yield of photoluminescence (PL), morphological superiority, high thermal stabilities, and ambipolar carrier transporting properties. [10][11][12][13] The fluorene molecule can be easily functionalized at its 9-position with long alkyl chain as a side moiety to bring in enhanced solubility into the rigid molecule. Furthermore, polyfluorene has an absorption band in the UV region, thus its emission spectrum covers the blue light zone.…”

Acridine-Triphenylamine Based Hole-Transporting and Hole-Injecting Material for Highly Efficient Phosphorescent-Based Organic Light Emitting Diodes

“…There is a hole-injecting layer (HIL), hole-transporting layer (HTL), emission layer (EML), electron-transporting layer (ETL), electron-injecting layer (EIL) embedded between two electrodes, the anode and cathode, which is known as a multilayer OLED structure. Multilayer OLED devices have improved the quantum efficiency when compared to single-layer devices [1][2][3][4]. Hole-transporting materials (HTM) play a major role to transporting holes from the anode to the emission layer and providing charge balance to prevent efficiency roll-off, since the hole transportation process faces critical issues, like thermal MA, USA) operating at 500 MHz.…”

Electroluminescent Behaviors of Electrochemically Cross‐Linkable Poly(benzyl ether) Terthiophene Dendrimers

“…An alternative approach is the use of fluorene derivatives, which, because of their high quantum yields, optical efficiencies, and high thermal stabilities, are interesting emissive materials for use in PLEDs. For example, fluorene‐carbazole dendrimers with a fluorene core unit and different numbers of carbazole and thiophene moieties have low turn‐on voltages (around 2.5 V) and bright green emissions with maximum luminance values of 25 400 cd m −2 . Moreover, instead of the carbazole moiety, a first‐generation blue‐green fluorene‐thiophene dendrimer was introduced that allows tuning of a blue emission …”