New Class of Wide Energy Gap Benzotriimidazole Optical Materials

A new class of wide energy gap benzotriimidazole materials have been synthesized by a two-step condensation reaction. All of the benzotriimidazole compounds have pi -pi(star) absorption bands in the range of 250-400 nm. The photoluminescence (PL) quantum efficiency of each benzotriimidazole depends strongly on the presence of electron withdrawing groups. PL quantum efficiencies of benzotriimidazoles without electron withdrawing groups were less than desirable (40-43%), while molecules with electron withdrawing groups displayed much stronger PL with efficiencies in the range of 73-75%. The electron withdrawing groups shift the emission to a longer wavelength, towards a more " true blue" color. This new class of benzotriimidazole optical materials could be used as electron-injecting and electron-transporting blue luminescence materials for potential organic light-emitting diode (OLED) applications.