Pronounced luminescence efficiency and thermal stability of small imidazole architect 2-(1, 4, 5-triphenyl-1H-imidazol-2-yl)phenol for efficient non-doped blue OLEDs

Abstract

A remarkable attention have been devoted to fabricate blue OLEDs, since it plays a vital role in the field of organic electronics particularly in full colour flat panel displays. Though, notable research outputs were emerged, it is still being a challenging task by the researchers to fulfil its essential criteria such as highly efficient, colour stable and long life-span materials. With the view to address the issues, herein we report an easy synthetic strategy under catalyst free condition for a single imidazole moiety, 2-(1, 4, 5-triphenyl-1H-imidazol-2-yl)phenol, (TSPI-1) with excellent emissive behavior and high thermal stability. OLED device utilizing TSPI-1 as an active layer with the configuration of ITO/PEDOT: PSS (40 nm) /TSPI-1 (60 nm)/ TPBi (30 nm) / LiF (1 nm)/Al (100 nm) displayed blue emission with the maximum brightness of 1.60 Cd/m2, CIE coordinates (0.17, 0.18) and the turn on voltage of 3.77 V. The synthesized imidazole derivative, TSPI-1 was well characterized by FT-IR, UV–vis, photoluminescence (PL), 1H &13C NMR, TGA-DTA, mass spectrometry and cyclic voltammetric (CV) studies. The results revealed the existence of localized electron density through non-planar geometry, specifically in solid state, good decay time, better morphological stability, (Tg = 111.93 °C) and high decomposition temperature (Td = 344 °C), therefore rendering it as a highly desirable material to fabricate OLED device under vacuum evaporation.