Non-doped deep blue emitters based on twisted phenanthroimidazole derivatives for organic light-emitting devices (CIE y ≈ 0.04)

The p-conjugation length of donor-acceptor molecules is not conducive to blue emission and the color purity of devices. Hence, by using a twisted donor-acceptor molecular design, we developed three deep-blue emitters, mtp, Tmtp and Cmtp. Compared to the TPA-BPI we reported previously, the subtle molecular modification and optimization shows extremely good color purity without impairing the excellent photophysical and electrical properties. The nondoped mtp-based device emitted deep-blue emission at 436 nm with CIE of (0.15, 0.05) and a maximum EQE of 3.89%. The Cmtp-based device emitted blue light of at 445 nm with CIE of (0.15, 0.07). Especially, the Tmtp-based device showed a violet-blue CIE coordinate of (0.15, 0.04).