Efficient Deep‐Blue Organic Light‐Emitting Diodes: Arylamine‐Substituted Oligofluorenes

Abstract

Abstract Novel deep‐blue‐light‐emitting diphenylamino and triphenylamino end‐capped oligofluorenes were synthesized by double palladium‐catalyzed Suzuki cross‐coupling of dibromo‐oligofluorene with the corresponding boronic acid as a key step. These oligofluorenes exhibit deep‐blue emission (λ em max = 429–432 nm), low and reversible electrochemical oxidation (highest occupied molecular orbital = 5.15–5.20 eV), high fluorescence quantum yield (Φ FL = 0.61–0.93), and good thermal properties (glass‐transition temperature, T g = 99–195 °C and decomposition temperature, T dec > 450 °C). Remarkably, saturated deep‐blue organic light‐emitting diodes, made from these oligofluorenes as dopant emitters, have been achieved with excellent performance and maximum efficiencies up to 2.9 cd A –1 at 2 mA cm –2 (external quantum efficiency of 4.1 %) and with Commission Internationale de l'Éclairage ( x , y ) coordinates of (0.152,0.08), which is very close to the National Television System Committee standard blue.