Performance-improved narrowband near-ultraviolet emission from a simple butyl and cyanogen substituted indolocarbazole

High-efficiency narrowband near-ultraviolet (NUV) organic light-emitting diodes with high color purity have currently encountered great challenges. Here, using butyl (Bu) and cyanogen (CN) substituted strategy in the simplest polycyclic aromatic hydrocarbons of indolocarbazole (ICz), two simple emitters of BuICz and BuICzCN were demonstrated. This simple strategy was observed to enable both emitters to realize NUV emission at 380–381 nm with a small full width at half maximum (FWHM) of 21–23 nm and high photoluminescent quantum efficiency of 50%–59% in toluene solution. Furthermore, the BuICzCN doped devices exhibited a slightly blueshifted narrowband NUV electroluminescence at 388 nm with a small FWHM of 32.3 nm but a higher external quantum efficiency of 3.92% in comparison with the BuICz doped devices. This work provides a path to realize high-performance narrow-band NUV emission.