Manipulating Excited States for Constructing Ultraviolet Hybridized Local and Charge Transfer Fluorophores and Non-Doped OLEDs with High Color Purity

The development of efficient ultraviolet (UV) organic light-emitting materials and devices holds paramount significance for their practical applications. Nonetheless, attaining a short-wavelength electroluminescence peak of less than 390 nm while maintaining high color purity in non-doped devices remains a formidable challenge. In this work, we have successfully designed and synthesized two UV hybridized local and charge transfer fluorophores, specifically 4DBF-CZCN and 2DBF-CZCN, which are comprised of cyanide-modified phenylcarbazole and a weak electron donor dibenzofuran. And the properties of excited state are well regulated through the different linking site of dibenzofuran. The resulting non-doped devices exhibit not only emission peak wavelengths of 390 and 388 nm, accompanied by narrow full-width-at-half-maximums of 42 and 38 nm, respectively, corresponding to color coordinates of (0.164, 0.034) and (0.164, 0.036), but also admirable external quantum efficiencies of 3.00 % and 2.86 % at high luminance levels of 1910 and 1252 cd m−2, respectively.