Non-doped deep-blue (λ<400 nm) organic light-emitting diodes (Conference Presentation)

Abstract

Organic light-emitting diode (OLED) has gain numerous attentions since an efficient OLED was firstly demonstrated by Tang and VanSlyke in 1987. Thanks to lots of efforts paid on their progress including materials and device architecture in past three decades, red and green OLEDs have great success in efficiency and lifetime. However, the development of high efficiency deep-blue counterparts with Commission Internationale de L'Eclairage (CIE) coordinate of y<0.1 currently remains in demand in the market of full-color display applications. For example, to realize the BT.2020 color space standard, the standard blue emission must have CIE coordinates of (0.131,0.046), and that is extremely challenging, especially in material development. Here, a new compound consisting of phenyls groups to connect a benzene core was successfully synthesized. The newly obtained compound exhibited a super wide bandgap of 3.5 eV and a deep-blue emission of approximately 397 nm as well as a photoluminescence quantum yield (PLQY) by 68% in thin film. Consequently, a non-doped OLED using the pristine new compound as emitting layer showed a peak efficiency of 4.9% in external quantum efficiency (EQE) and deep-blue emission with CIE coordinates of (0.16, 0.04). Note that the OLED configuration was bottom emission, which meant the such deep-blue emission resulted from the material itself, rather than microcavity effect. Grazing incidence wide-angle X-ray scattering (GIWAXS) of new compound displayed an order parameter (SGIWAXS) of 0.44, indicating molecules primarily aligned horizontally to the substrate, which contributed to the high efficiency.