Development And Polymer Light-emitting Diode Application Of Near-infrared Luminescent Iridium(Ⅲ) Complex Doped Or Grafted Into Organic Polymer

Near-infrared organic light-emitting diode（NIR-OLEDs）with the potential application in national defence,optical communication and optical fiber,has attracted wide attention due to its self-luminescence,high quantum efficiency,flexible display and simple process.This thesis is focused on the development of NIR-PLED（polymer light-emitting diode）with low-cost and large-area display,where two kinds of NIR-emitting layers are considered.Firstly,using the NIR luminescent iridium complex as the guest,its doping into to the host polymeric material is adopted.On the other hand,through the covalent-bonding of the the NIR luminescent iridium complex into the PF host by Suzuki coupling reaction,the grafting-type inorganic-organic polymer is obtained.In the meantime,based on their good NIR luminescence and physical properties such as good mechanical intensity,high thermal stability and easy-going solution-processing ability,NIR-PLEDs with desirable electroluminescent properties are expected.The main content is as follows:1、Toward the good NIR luminescence of the iridium（III）complex:The reaction of the benzothiophene ligand Hiqbt（Hiqbt=1-（benzo[b]thiophen-2-yl）isoquinoline）as the main ligand and the Br-modified Schiff-base ligand HL（HL=（E）-4-bromo-2-（（phenylimino）methyl）phenol）as the ancillary ligand with IrCl₃·3H₂O,gives rise to the expected iridium（III）complex[Ir（iqbt）₂（L）].Further based on the structural characterization by EA,FT-IR,¹H NMR and XRD,its photo-physical property included good NIR luminescence is also studied.2、Based on the Suzuki coupling reaction of the Br-modified iridium complex[Ir（iqbt）₂（L）]for the formation of Poly（PF-[Ir（iqbt）₂（L）]）,the thermal stability was tested by thermogravimetric analysis（TG）,and the photophysical properties included NIR luminescence were also investigated.3、Using the near-infrared luminescent iridium complex[Ir（iqbt）₂（L）]as the guest,its doping into PVK-OXD-7 host was adopted to fabricate the single-layer NIR-PLED-I device withtheconfigurationofITO/PEDOT:PSS（4nm）/PVK（65%）:OXD-7（30%）:[Ir（iqbt）₂（L）]-（5%）（120 nm）/LiF（1 nm）/Al（100 nm）,exhibiting the emissive wavelength of707 nm,the turn-on voltage of 12 V,the maximum external quantum efficiency of 1.065%,and the maximum brightness of 2.83 cd·m^-2.Upon the further optimization for single-layer device NIR-PLED-II(ITO/PEDOT:PSS（40 nm）/PVK（65%）:OXD-7（30%）:[Ir（iqbt）₂（L）]-（5%）（120 nm）/TmPyPB（15 nm）/LiF（1 nm）/Al（100 nm）,exhibiting the emissive wavelength of 709nm,with TmPyPB-assisted electron-transport promoting,the electroluminescent performance was significantly improved to give the maximum external quantum efficiency of 1.391%and the maximum brightness of 1.70 cd·m^-2.4、Taking the grafting-typed material Poly（PF-[Ir（iqbt）₂（L）]）as the light-emitting layer,another kind of NIR-PLED device was fabricated with the configuration of ITO/PEDOT:PSS（40 nm）/Poly（PF1-[Ir（iqbt）₂（L）]）（80 nm）/TPBi（40 nm）/LiF/Al.Its electroluminescence property indicated that under the condition of high driving voltage,the main light-emitting position gradually shifted to the near-infrared region（708 nm）,and the EL emission peak intensity in the near-infrared region can be continuously increased.When the driving voltage is 8 V,the maximum external quantum efficiency reaches 0.06%.