Positional Isomers of Phenylacridine/Spirobifluorene as Deep‐Blue Fluorescent Emitters for Organic Light‐Emitting Diodes

Abstract

AbstractDesigning deep‐blue fluorophores with a low CIEy is an important request for organic light‐emitting diode (OLED) technology either for display applications or to develop new applications such as light source with antibacterial properties. The challenge of deep‐blue emitting OLEDs mainly relies on the difficulty to reach efficient emitters fulfilling all the characteristics desired to insure a high device performance with suitable CIE coordinates. Herein, we report on the synthesis, the physico‐chemical properties and the application as emissive layer in an OLED of two deep‐blue emitters constructed on the association of Spirofluorene‐N‐PhenylAcridine (SPA‐F) and SpiroBiFluorene (SBF) molecular fragment. Two emitters, 2,2‐SPAF‐SBF and 2,3‐SPAF‐SBF have been constructed following a similar design strategy. The emission wavelength is tuned by the substitution pattern of the SBF backbone (meta or para linkage). Through a structure/properties relationship study, the electrochemical, photophysical and thermal/morphological properties are discussed. When used as emitter in a multi‐layer OLED, 2,2‐SPA‐SBF displays a deep‐blue emission reaching an EQE of ≈1.7% and a Von of 4 V. The electroluminescent spectrum displays a λmax below 400 nm (i.e. 394 nm) and CIE coordinates of (0.182, 0.054). The CIEy coordinate of 0.054 is low and fits the NTSC and EBU standards.