Synthesis And Properties Of Near-Infrared-Emitting Dinuclear Platinum Complexes With Oxadiazole And Polymers With Benzothiadiazole Units

With the rapid development of optical fiber communication,night display and biological imaging technologies,near-infrared(NIR)luminescent materials have attracted close attention due to their wide application in various fields.In addition,organic near-infrared luminescence materials with the advantages of simple preparation process,low cost and easy structure regulation have become one of the most potential and promising research fields.The research progress of cyclometalated platinum complexes NIR organic light-emitting devices and polymer near-infrared light-emitting electrochemical cells is reviewed.Aiming at the key problems such as the difficulty in red-shift of emission spectrum of organic near-infrared luminescence materials and the low luminescence efficiency caused by the low energy level band gap,in this paper,we designed and synthesized the near-infrared electroluminescence materials of dinuclear cyclometalated platinum complexes based on oxadiazole-thiol and doped-polymer based on benzothiazole,moreover,the corresponding organic electromechanical luminescent device was made and their performance were studied.The main research contents and results are as follows:1.We synthesized three complexes(piq)2Pt2(?-PhOXT)2,(piq)2Pt2(?-C8OXT)2 and(2niq)2Pt2(?-C8OXT)2.The effects of different conjugated ring metal ligands on the photophysical,electrochemical and electroluminescent properties of binuclear ring metal platinum complexes were studied.Using these three dinuclear cyclometalated platinum complexes as the emitter,we made the polymer light-emitting diodes(PLEDs),obtaining the most red-shift emission peak of 706 nm and a maximum external quantum efficiency(EQE)of 8.86%with a radiance of 986 ?W cm-2.2.Four complexes(niq)2Pt2(?-C8OXT)2,(nq)2Pt2(?-C8OXT)2,(2niq)2Pt2(?-C8OXT)2 and(2nq)2Pt2(?-C8OXT)2 with different naphthyl-quinoline isomers were synthesized.The effects of the isomeric structure of main ligands on the photophysical,electrochemical and electroluminescent properties of the complexes were studied.The results show that the device properties of complexes containing 2-naphthalene substituted ligands are better than those containing 1-naphthalene substituted ligands,not only the wavelength has red-shift,but also the EQE is improved.3.Two complexes(TPAiq)2Pt2(?-C8OXT)2,(TPAniq)2Pt2(?-C8OXT)2 with D-A structure ligands were synthesized.The effects of the D-A structure of main ligands on the photophysical,electrochemical and electroluminescent properties of the complexes were studied.The results show that introducing naphthyl into the ligand will redshift the emission,but due to the band gap law and incomplete energy transfer from the host,the property of EQEs will be negatively affected.4.Two complexes(tiq)2Pt2(?-C8OXT)2 and(btiq)2Pt2(?-C8OXT)2 with ligands which contain heteroatom S were synthesized.The effects of heteroatom S on the photophysical,electrochemical and electroluminescent properties of the complexes were studied.The results showed that when thiophene ring expanded conjugation into benzothiophene ring,the emission spectrum of the complex can be effectively redshifted,and EQE also can be slightly improved by device optimization.5.By adjusting the length of the alkyl chain of the auxiliary ligand to synthesize dinuclear cyclometalated platinum complexe(2niq)2Pt2(?-PhOXT)2,(2niq)2Pt2(?-t-BuOXT)2,(2niq)2Pt2(?-C6OXT)2 and(2niq)2Pt2(?-C12OXT)2.The effects of the alkyl chain structure on the photophysical,electrochemical and electroluminescent properties of the binuclear ring metal platinum complexes were studied.The results show that alkyl chain has little effect on the luminescence spectrum,but has significant effect on the external quantum efficiency.The introduction of alkyl chain can improve the solubility of complex,inhibit the aggregation quenching of complexes and improve the EQE.6.We used benzodithiophene(BDT)and benzotriazole(BTz)and the derivatives as the host,and thiophenyl benzothiazole(TBT)as the emitter to synthesize three copolymers PBDTBTz-TBT,PBDTTBTzT-TBT and PBDTTBTzFT-TBT.The effects of the host structure of the polymer on the photophysical,electrochemical and electroluminescent properties of the polymer were studied.The light-emitting electrochemical cells(LEC)comprising the three host-guest copolymers were made.One of them delivered NIR emission(?peak?723 nm)with a high radiance of 169?W/cm2 when driven by a low voltage of 3.6 V.This NIR-LEC also featured good stability,as manifested in that the peak NIR output from a nonencapsulated device after 350 h of continuous operation.