Supramolecular π−π Stacking Pyrene-Functioned Fluorenes: Toward Efficient Solution-Processable Small Molecule Blue and White Organic Light Emitting Diodes

Abstract

In this paper, we described a new category of solution-processible small molecule organic light emitting materialssthe pyrene-functioned diarylfluorenes: 2PPPF and DPPPF. In solution, both of the materials show deep blue emission. In film, their emission largely red-shifted due to strong π-π stacking of pyrene groups. 2PPPF, which is quite rigid in molecular structure, bearing only one alkoxyl group, could form smooth film by spin-coating. From the photoluminescence and morphology study, we believe the strong π-π stacking enhanced the film forming ability. 2PPPF is an amorphous blue light emitter, with a T g over 100 °C and T d over 430 °C. The good thermal stability is comparable to polymeric light emitting materials. The material shows strong aggregated emission with a broad structureless peak at about 460 nm in film. Electroluminescent devices by spin-coating were successfully fabricated. A single-layered device using 2PPPF as the active material shows a turn on voltage of 4.3 V, brightness over 3600 cd/m 2 , and current efficiency up to 1.30 cd/A. When 2PPPF was blended into PVK, the single-layered device takes on deep blue emission with the CIE 1931 coordinates at (0.16, 0.10). Single-layered white organic light emitting diodes using 2PPPF:MEHPPV blend as the bulk emitter had a maximum current efficiency up to 1.84 cd/A and brightness over 5700 cd/m 2 .

Synthesis of Light‐Responsive Pyrene‐Based Polymer Nanoparticles via Polymerization‐Induced Self‐Assembly

“…The monomer conversion remained low (<30%) when compared with the conversion obtained by homogenous RAFT polymerization of PyMA monomer in dioxane (Table S1, Supporting Information). We postulate that this is due to the π–π stacking of the pyrene moieties which inhibits the monomer diffusion to the core of nanoparticles and subsequently limits the monomer conversion . π–π stacking (pyrene excimer formations) is the result of strong interactions between pyrene units on the polymer chains .…”

Pyrenoimidazole‐Based Deep‐Blue‐Emitting Materials: Optical, Electrochemical, and Electroluminescent Characteristics

“…[20] However, by making subtle structural variations, in particular through the introduction of sterically demanding groups, such as tert-butyl or diarylamine units, pyrene derivatives have been tuned to exhibit useful emission characteristics. [20] However, by making subtle structural variations, in particular through the introduction of sterically demanding groups, such as tert-butyl or diarylamine units, pyrene derivatives have been tuned to exhibit useful emission characteristics.…”

White and Saturated Blue Phosphorescent OLED based on the Non-Emissive Homoleptic Complex Ir(ppz)3 as single active material

“…However, serious problems are evidenced in multilayer white OLEDs such as the reproducibility of the device preparation, the variation of the Commission Internationale de l'Eclairage (CIE) coordinates as a function of the driving voltage or the unequal aging of the di erent emitters conducing to an emission change over the time. Conversely, WOLEDs incorporating a single emitter are quite few [7][8][9][10][11][12]. In this case, a higher stability of the emission color with the driving voltage and enhanced lifetimes are demonstrated.…”