Enhancing Triplet–Triplet Annihilation Upconversion Performance Through Anthracene–Carbazole Interactions for Organic Optoelectronic Applications

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%. Carbazole‐modified anthracene derivatives enable high upconversion efficiency through well‐aligned Tm, Sn, and 2×E(T1) states. Local excitation during the S1 to S0 transition ensures high photoluminescence quantum yields. Organic light‐emitting diode (OLED) devices exhibit an external quantum efficiency (EQEmax) of 5.82% in neat films and 11.12% in bilayer structures.