Polarization And Upconverted Circularly Polarized Luminescence Of Luminescent Liquid Crystal

Luminescent liquid crystal materials had a bright future in backlighting for conventional liquid crystal displays due to its unique mesomorphic and luminescent properties.However,most of the reported liquid crystal luminescent materials have low luminescent efficiency and there are scarce researches on their polarized luminescent properties.In view of this situation,this paper focuses on the polarization properties of luminescent liquid crystal materials.The main contents of this paper are listed below:1?Two kinds of platinum-based metallomesogens Pt1 and Pt2 have been designed and synthesized,in which the cyclometalating platinum complex was used as the luminescent core and the mesogenic unit was induced in the ancillary ligand.The structure of these molecules has been confirmed by ¹H NMR,¹³C NMR,MALDI-TOF mass and X-ray single-crystal diffraction.In addition,their photophysical electrochemical and thermal properties have been measured by UV-Vis absorption spectrum,photoluminescent spectrum,cyclic voltammetry,thermal analysis and polarized optical microscopy.The results indicated that the complex Pt1displayed the enantiotropic nematic phase and showed the intense emission both in solution and in the neat film.However,the complex Pt2 displayed the smectic A phase and observed the weak emission in solution.We also explore the polarised properties of complex Pt1 after the rubbing and annealing procedures.The broad polarised EL spectra with a polarised ratio of 1.33 was achieved,the maximum current efficiency was 1.7 cd A^-1 and the highest external quantum efficiencies?EQE?was 1.1%.2?In order to achieve the upconverted emission and the upconverted circularly porlarized luminescence in the liquid crystal.We prepared the luminescent liquid crystal,which achieved the circularly polarized luminescence,upconversion and upconverted circularly polarized luminescence by blending the chiral acceptor molecule R?S?1 and the achiral sensitizer PtOEP into the room-temperature nematic liquid crystal.We carefully examine the photophysical properties and the mechanism of luminescence by using the CPL spectrum,UC emission spectrum and the UC-CPL spectrum.The results showed that the chiral molecule R?S?1 could not only induce the nematic liquid crystal to generate the chiral nematic liquid crystal?N*LC?,but also achieve the triplet–triplet annihilation-based photon upconversion by being as the upconverted acceptor.The UC quantum yield of this N*LC was 13%,the g_lum of CPL and UC-CPL was 0.2 and 0.04,respectively.