Synthesis And Properties Of Luminescent Liquid Crystal Materials Based On Platinum(â…¡) Containing Triphenylene Unit

Luminescent liquid crystal materials and the polarized organic light-emitting diodes(OLEDs) have been attracted much attentions due to the potential application of polarized OLEDs in the backlight of liquid crystals displays(LCDs). In order to enrich the luminescent liquid crystal materials, improve the carriers mobilities and polarized efficiency, in this thesis, two series of cyclometalated platinum complexes have been designed and synthesized, in which the platinum complexes employ the triphenylene-phenylpyridine derivatives as cyclometalated ligands and use the acetylacetone/1,3-diphenylpropane-1,3-dione derivatives as ancillary ligands. All of the targeted platinum complexes were confirmed by 1H NMR, 13 C NMR, TOF-Mass and elemental analysis. At the same time, the liquid crystal properties, photophysical properties and electrochemical properties were investigated by TGA, DSC, POM,XRD, UV-vis, PL and CV. The polarized OLEDs using platinum complexes as the dopant and employing PFO as the host matrix were fabricated. Finally, the single-dopant polarized white OLEDs with a polarized ratio as high as 1.32 were achieved. The main research contents of this thesis are listed below:1、Four D-A type cyclometalated platinum complexes, named as Pt1、Pt2、Pt3、Pt4 were designed and prepared, in which the triphenylene is considered as mesogenic unit and phenylpyridine as the acceptor unit. Pt2 were evaluated as the liquid crystal with column phase in the range of 55-110 oC via DSC, POM and XRD.All of these platinum complexes show intense emission at 550 nm in dichloromethane solution. Furthermore, the annealing film of Pt1 and Pt2 exhibit a hole mobilities of2.5 × 10-4 cm2V-1s-1 and 2.99 × 10-5 cm2V-1s-1, respectively. This result indicates that both of these cyclometalated platinum complexes show a good hole mobility compared to the reported platinum complexes.2、In order to study the effect of conjugated/non-conjugated structure on the liquid crystal and photophysical properties of platinum complexes, two series of cyclometalated platinum complexes(Pt5/Pt6/Pt7/Pt8/Pt9/Pt10) based on triphenylene unit and phenylpyridine-cabarzole derivatives were designed and synthesized. The liquid crystal properties and photophysical properties of these platinum complexes were explored in detail. The influence of cabarzole group on the liquid crystal properties and photophysical properties of platinum complexes were investigated. Additionally, the emission at different phase state, electroluminescenceand polarized emission of Pt5 and Pt6 were systematically studied. Interestingly, the polarized OLEDs employing Pt6 as single dopant and using PFO as host matrix were fabricated. The polarized ratio as high as 1.32 is achieved, which is the first time to report the polarized white OLEDs based on cyclometalated platinum complexes.