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
Sandhya Rani Nayak, Jaipal Devesing Girase, Mangey Ram Nagar, Jwo‐Huei Jou, Sivakumar Vaidyanathan
Abstract
Blue emitters with outstanding luminous performance must be synthesized for full-color organic light-emitting diode displays. The hybridized local and charge transfer (HLCT) is a remarkable excited state that combines the local and CT state to ensure a significant fluorescence quantum yield. The ambition of this study is to implement a subtle interpretation of photophysical and electroluminescence (EL) properties. To understand more about the geometry and orientations, the density functional theories were studied. Herein, we present a hybrid donor-π-acceptor blue-emitting fluorophore with a twisted geometry, in which triphenylamine (TPA) acts as a donor, 9,9 diethylfluorene acts as a spacer, and benzilimidazole acts as an acceptor. The EL spectra of the device are very similar to spectra of photoluminescence in the solution phase. Among all, the best performing 15 wt % MCFBI-fl-TPA-based OLED device illustrates a maximum luminance of 3290 cd/m 2 . The device shows 8.2 lm W –1 of power efficiency, 7.9 cd A –1 of current efficiency, and 3.5% of high external quantum efficiency with (0.20, 0.23) of CIE coordinates of the device emitting blue color.