Superior electron mobility, red electroluminescence with high quantum efficiency from printable room temperature columnar liquid crystalline perylene bisimide

Synthesis of highly fluorescent compounds is currently a critical requirement to facilitate the economical and metal-independent manufacture of organic light-emitting diodes (OLEDs) on a large scale. This study presents a highly soluble, swallow tail based electron deficient perylene bisimide (PBIST) exhibiting room temperature columnar oblique (Colob) liquid crystalline behavior along with a high photoluminescence quantum yield, positioning itself as a promising candidate for efficient OLEDs. Incorporation of swallow tails helped in enhancing the solubility and reduction of the clearing points. This unique tailor-made molecular design with the liquid crystalline phase allowed a demonstration of n-type field effect mobility of 0.008 cm2 V−1s−1 when annealed in the liquid crystalline mesophase range (at 70 °C) which can be exploited in the fabrication of printable electronic devices. Capitalizing on the high charge transport and luminescence attributes of PBIST, a series of devices were fabricated by utilizing PBIST as a single emitter and dispersed at different concentrations of 0.3, 0.5 and 1 wt% in host material CBP. Impressively, doped devices featuring the CBP as a host at a 0.5 wt% PBIST concentration exhibited an external quantum efficiency (EQE) as high as 7 %, accompanied by a luminance of 1787 cd/m2. The high EQE is attributed mainly to the triplet–triplet annihilation (TTA) process. This notable EQE enhancement signifies a substantial stride towards expanding the utility of multifunctional columnar self-assembled materials for the advancement of OLEDs.