Search

Three carbazole‐substituted anthracene 2CbzAn, 26CbzAn, and 246CbzAn have been developed. The introduction of these carbazole substituents could generate more triplet states with energy levels close to 2× E(T1) that could successfully facilitate the triplet‐triplet annihilation upconversion (TTA‐UC) process to achieve high upconversion quantum yield (UCQY). This observation aligns with the Adachi theory about TTA‐UC mechanisms. In organic light‐emitting diode (OLED) device investigation, in a non‐doped state show an external quantum efficiency (EQEmax) of 5.82% with exceptional pure‐blue emission (CIEy of 0.101), and the DPaNIF doped DMPPP/26CbzAn bilayer structure reaches an impressive EQEmax of 11.12%. [ABSTRACT FROM AUTHOR]

Based on the classic 1,1′:4′,1″‐terphenyl fluorophore, a novel near‐ultraviolet (NUV) fluorescent BB4Ph (4,4″′‐bis(2,3,4,5‐tetraphenylphen‐1‐yl)(1,1′:4′,1″‐terphenyl) is designed, synthesized, and characterized. BB4Ph exhibits a NUV fluorescence with a λmax of 373 and 380 nm in solution and as a thin film, respectively. The grazing incidence wide‐angle X‐ray scattering (GIWAXS) reveals BB4Ph having a high value of order parameter (SGIWAXS) of 0.59 for a molecular layer array normal to the substrate; the angle‐dependent photoluminescence (ADPL) measurement shows Θ (horizontal–dipole ratios) as high as 95% with the neat film. The non‐doped BB4Ph organic light‐emitting diodes (OLEDs) show external quantum efficiency (EQE) up to 5.24% with 1931 Commission Internationale de l' Eclairage coordinates (CIEx,y) of (0.16, 0.04), a NUV electroluminescence. With 4P‐Cz (9,9′‐(1,1′:4′,1″:4″,1′″‐quaterphenyl‐4,4′″‐diyl)dicarbazole) as a dopant emitter, doped BB4Ph OLEDs show the highest EQE of 6.99% and a NUV 1931 CIEx,y (0.16, 0.04). The photoluminescence quantum yield is measured for the thin film of BB4Ph and 4P‐Cz:BB4Ph as 68% and 96%, respectively. Hence, the low limits of light outcoupling efficiency (ηout) of the two individual OLEDs are estimated as 31% and 29%, respectively. [ABSTRACT FROM AUTHOR]