Design,Synthesis And Photoelectric Properities Of High Efficiency OLEDs Dopants Based On Platinum(?) Complexes

Since organic light emitting diodes(OLEDs)were reported by C.W.Tang and S.A.VanSlyke in 1987,OLEDs have attracted great attention from the scientific and industrial communities because OLEDs have many advantages such as high brightness,wide viewing angle,and large operating temperature range.However,the high efficiency emitting materials are still desirable for the high performance OLEDs.The phosphors dopants based on transition metals can achieve theoretical internal quantum efficiency of 100%via harvesting both singlet and triplet excitions by the taking the advantage of strong spin-orbit coupling of metal ions.So it is important to develop novel and highly efficiency phosphors dopants.When Pt(II)ion is coordinated by a tetradendate ligand,it is an effective solution to reduce the probability of non-emissive decay by suppressing the vibration and rotation around metal ions.Thus,in this thesis,our works focused on the design and synthesis of new tetradendated Pt(II)complexes and the study of their electroluminescence properties.This thesis included mainly two parts:1.Ptl and Pt2 based on picolinic acid and spirofluorene units were designed and synthesized.The introduce of spirofluorene group can effectively suppress the aggregation in the solid state and reduce the formation of excimer and further minimize the triplet-triplet annihilation(TTA).So the CIE coordinates of devices were shifted slightly at different doping ratios.On the other hand,both complexes contain picolinate group,which has a high ligand field strength and can stabilize the occupied d orbitals and facilitate d-?*transition energy of Pt(II)complexes.The OLEDs based on these Pt(II)complexes showed high EL performance.Remarkably,the device based on Ptl at the doping ratio of 15 wt%achieved a maximum efficiency of 83.0 cd A-1,63.8 lm W-1 and 22.9%with CIE coordinates of(0.36,0.60).The device based on Pt2 at the doping ratio of 10 wt%achieved a maximum efficiency of 74.0 cd A-1,63.9 lm W-1 and 20.2%.Notably,Pt2 demonstrated low EQE roll-off about 3.5%at a brightness of 1000 cd m-2.2.LPtl-LPt3 based on diphenyl ether functional group were prepared.The LUMO levels of these complexes could be efficiently tuned by the introduce of pyrazolopyridine,aromatic amine and spirofluorene groups.As a result,OLEDs based on these materials showed green to blue-green electroluminescence.Particularly,,these Pt(II)complexes can reduce the intermolecular interaction by use of large steric hindrance groups,such as aromatic amine and spirofluorene groups.The device based on LPtl at the doping ratio of 10 wt%achieved a maximum efficiency of 31.0 cd A-1,25.9 lm W-1 and 10.2%.Notably,the driving voltage was 3.2 V for device based on LPtl.The CIE coordinates of LPt2 and LPt3 were(0.22,0.40)and(0.22,0.34),indicating these two complexes were blue-green dopants.