ZDL

Fine energy-level modulations of small-molecule acceptors (SMAs) are realized via subtle chemical modifications on strong electron-withdrawing end-groups. The two new SMAs (IT-M and IT-DM) end-capped by methyl-modified dicycanovinylindan-1-one exhibit upshifted lowest unoccupied molecular orbital (LUMO) levels, and hence higher open-circuit voltages can be observed in the corresponding devices. Finally, a top power conversion efficiency of 12.05% is achieved.

Two iridium complexes with chiral pinene sterically hindered substituents are applied in organic light-emitting diodes. Highly efficient devices show a maximum luminance of 135 676 cd m⁻², a maximum current efficiency of 103.50 cd A⁻¹, a maximum external quantum efficiency of 28.0%, and a maximum power efficiency of 88.29 lm W⁻¹ with a slight efficiency roll-off.

Novel symmetrical anthracene derivatives with bulky carbazolyl-fluorene, diphenylamino-fluorene, or carbazolyl-carbazole units connected to the anthracene frame through an ethynyl bridge were synthesized in excellent yield by using Sonogashira cross-coupling. The ethynyl bridge in the anthracene dyes increases π-electron conjugation and the bulky substituents considerably attenuate intermolecular interactions. The dyes possess high thermal stability, tremendous solubility in common organic solvents, and especially high photoluminescence quantum yield (Φ_f) in solution in the range of 77–98 %. OLED devices were fabricated. The AFM images of thin films and blends prepared from all compounds show a uniform and flat surface, indicating excellent film-forming properties. Devices incorporating the anthracene derivative with diphenylamino-fluorene end-capping groups exhibited the highest value of current density (J). All of the fabricated OLED devices emitted yellowish-orange light under applied voltage.

Symmetrical anthracene derivatives with bulky units connected to the anthracene frame through an ethynyl bridge were synthesized and their electrochemical, photophysical, and electrical properties were characterized. The compounds were yellowish-orange emitters with high thermal stability, had excellent solubility in most organic solvents, and very high photoluminescence quantum yield in solution.