Fluorinated Phenoxy Boron Subphthalocyanines in Organic Light-Emitting Diodes

Three fluorinated BsubPcs have been synthesized and characterized. Crystals suitable for XRD were grown by slow vapor diffusion and sublimation. Analysis of their crystal structures revealed a dimeric association of BsubPc units for F5BsubPc and columnar packing for F12BsubPc and F17BsubPc. Cyclic volatmmetry (CV) was used to probe the frontier orbital energy levels of these compounds in both dichloromethane and acetonitrile solution; however, only F5BsubPc underwent oxidative events, whereas all three compounds underwent reductive events. A −362 and −37 mV shift in the reductive peak potential was observed for peripheral and axial fluorination, respectively, as measured by cyclic voltammetry. Solution UV−vis absorption and photoluminescence spectra were measured in dichloromethane. All three compounds demonstrated air-stable n-type conductivity in single-carrier devices and extremely narrow orange EL emission with a fwhm of only ∼30 nm. F5BsubPc showed a maximum luminescence of 122 cd/m2 at 8 V, with a maximum current efficiency of 0.03 cd/A, whereas the devices fabricated from F12BsubPc and F17BsubPc produced luminescence with a maximum value of <1 cd/m2.