Solution Processable Deep-Blue OLEDs Based on Benzimidazole-TPA Conjugated through 9,9-Diethyl Fluorene (D-π-A) Luminophore with a Hybridized Local and Charge Transfer Excited State

Blue emitters with outstanding luminous performance mustbe synthesizedfor full-color organic light-emitting diode displays. The hybridizedlocal and charge transfer (HLCT) is a remarkable excited state thatcombines the local and CT state to ensure a significant fluorescencequantum yield. The ambition of this study is to implement a subtleinterpretation of photophysical and electroluminescence (EL) properties.To understand more about the geometry and orientations, the densityfunctional theories were studied. Herein, we present a hybrid donor-pi-acceptorblue-emitting fluorophore with a twisted geometry, in which triphenylamine(TPA) acts as a donor, 9,9 diethylfluorene acts as a spacer, and benzilimidazoleacts as an acceptor. The EL spectra of the device are very similarto spectra of photoluminescence in the solution phase. Among all,the best performing 15 wt % MCFBI-fl-TPA-based OLED device illustratesa maximum luminance of 3290 cd/m(2). The device shows 8.2lm W-1 of power efficiency, 7.9 cd A(-1) of current efficiency, and 3.5% of high external quantum efficiencywith (0.20, 0.23) of CIE coordinates of the device emitting blue color.