D-π-A Type [7]Helicene-like Imide Derivatives with Tunable Photophysical Properties and Circularly Polarized...

Helicenes and their derivatives show great application prospects as circularly polarized luminescence (CPL) materials, but their fluorescence quantum yields (Φ_FLs) need a breakthrough urgently. Herein, we reported a series of D-π-A type helical luminescent emitters by combining the [7]helicene-like imide acceptor with five different donors. The obtained five emitters display blue-to-orange luminescence and markedly enhanced Φ_FL. Notably, TPA-NiBTI exhibits the maximum Φ_FL in solution, while TPE-NiBTI achieves a maximum Φ_FL in the solid state. Their two pairs of enantiomers, (P/M)-TPA-NiBTI and (P/M)-TPE-NiBTI, exhibit remarkable CPL activities, and their doped PS film both displayed doubled Φ_FLs. Among them, [(P/M)-TPE-NiBTI]-doped PS film exhibits the maximum luminescence dissymmetry factor (|g_lum|) value of 9.0×10^-4 and the maximum Φ_FL of 22 %. This molecular design strategy presents a promising approach to improving the Φ_FL of helicene derivatives, thereby facilitating their potential application into chiral optoelectronic devices.