AIEE-active V-shaped fused-biscoumarins: synthesis, photophysical and electroluminescence properties

Abstract

V-shaped fused-biscoumarins have attracted considerable attention due to their interesting photophysical properties derived from the π-extended molecular frameworks, which could have the opportunity to be used in constructing optoelectronic materials. However, V-shaped fused-biscoumarins as electroluminescence materials easily suffer from aggregation-caused quenching (ACQ) in the solid state due to the presence of a large conjugate plane of the V-shaped fused-biscoumarin framework. To suppress the aggregation-caused emission quenching as well as increase the hole-transporting capability, three AIEE-active V-shaped fused-biscoumarin derivatives, namely, CC-TPA, CC-TPE and CC-TriPE, were successfully designed and synthesized by the introduction of triphenylamine (TPA), tetraphenylethene (TPE) and triphenylethene (TriPE) groups into the V-shaped fused-biscoumarin core. These compounds exhibited strong green emission in CH₂Cl₂ solution and yellow or red emission in thin solid films and displayed good thermal stability. Moreover, solution-processed doped devices with a configuration of ITO/PEDOT:PSS (30 nm)/PVK:PBD (7 : 3 wt%):CC derivative (x wt%) (30 nm)/TPBi (35 nm)/Liq (2 nm)/Al (200 nm) were fabricated by the solution processing method, among which the CC-TPA-based doped device exhibited a maximum luminance (L_max) of 3054 cd m⁻², a maximum current efficiency (CE_max) of 6.81 cd A⁻¹ and a maximum external quantum efficiency (EQE_max) of 2.13%, respectively.