Electronic and optical properties of Phenanthroimidazole-Alkyl spacer-Carbazole based fluorophores for ultraviolet emissive Organic Light-Emitting Diodes

Abstract

Bipolar behavior of Phenanthroimidazole has great capability to design efficient near UV deep blue emission. The different substitution at N1 and C1 centre of the imidazole moiety further enhance the optical and electronic properties. At the same time, alkyl spacer precise the stacking via π-π interaction and intermolecular aggregation, which leads to enhance photoluminescence quantum yield of thin film 74%. All the materials exhibit near UV deep blue region and electroluminescence spectra exhibited between 395-420 nm. Fabricated the OLED doped device by using the host matrix as CBP with the same configuration as non-doped device to further enhance the device efficiency and color purity. CBP selectively used as a host because it possesses appropriate HOMO and LUMO levels matched with the synthesized emitters which help in efficient charge trapping. Primarily, the device doped with fewer concentration (0.5 wt%) of the emitters performed an splendid device efficiency and luminance properties. The great achievement of 0.5 wt% OLED device of PIPP exhibit a highest luminance of 1202 cdm-2, a power efficiency (PE) of 2.2 lm/W, a current efficiency (CE) of 2.7 cd/A, and maximum external quantum efficiency (EQE) of 4.4% with Commission International de L’Eclairage (CIE) coordinates of (0.17, 0.10) emits deep blue