Circularly Polarized Emission from Mixture of Vacuum-Evaporated Mesogenic Luminophores

Direct circular polarized (CP) emission from a twisted mesogenic luminophore is one of the promising approaches for generating high degree of CP light since device parameters governing the degree of CP emission are easily controlled. Most high CP emissions have been performed by solution process since a twisted structure of mesogenic luminophore is easily achieved. However, since solution process has been impeded by the limitation of low resolution and efficiency, vacuum evaporation has been commonly used in display industries to obtain high performance and resolution. Here, high CP electroluminescence (CPEL) with a dissymmetric factor of 0.914 is demonstrated through the sequential vacuum evaporation of two mesogenic luminophores and chiral agent. The sequentially evaporated luminophores and chiral agent are converted into a mixture by thermal annealing, and the luminophore mixture constructs a twisted structure and generates resultantly high CPEL. The electroluminescence device fabricated with the mixture exhibits three times higher luminance and two times higher efficiency than the devices with each single luminophore. Further, the dissymmetric factors according to the device parameters based on the Stokes parameter analysis are theoretically investigated. It is anticipated that the approach paves the way toward improving CPEL performance.

Automated summary

High circular polarized electroluminescence (CPEL) with a high dissymmetric factor was achieved by sequentially vacuum evaporating two mesogenic luminophores and a chiral agent, resulting in a twisted structure and improved luminance and efficiency in the electroluminescence device. The approach is expected to pave the way for enhancing CPEL performance.