The Synthesis And Photoelectric Properties Of Phosphorescent Cyclometalated Iridium (Ⅲ) Complexes And The Small Molecule Donor Materials

Organic electroluminescence device（OLED）have be considered as the next-generation display and lighting device,because of the advantage of low energy consumption,high brightness,adjustable color,soft color,no backlight,low starting voltage.OLED which use organic phosphorescent iridium（Ⅲ）complex as the gust material dopant into host material can harvest the singlet state exciton and triplet state exciton in the effect of spin-orbit coupling（SOC）,so that can achieve 100 percent quantum efficiency in theory.Organic phosphorescent iridium（Ⅲ）complex can tuning the phosphorescence color via ligand structure control occurs through LUMO control or change the frontier orbital energies through electron-donating or withdrawing substituents.In this article,we have synthesized organic phosphorescent iridium（Ⅲ）complexes based on dibenzothiophene-5,5-dioxide,then applicated them on fabrication white organic light-emitting devices and investigated their photoelectricity property.We also interested in small-molecule donor materials,so we have synthesized three different small-molecule donor materials based on 2,1,3-benzoselenadiazole as the electron acceptor,then we use fullerene PC₇₁BM as the acceptor material to fabricate bulk heterojunction solar cell and investigated the devices performance.In chapter 2,we have used carbazole as the electron donor unit,dibenzothiophene-5,5-dioxide as the electron acceptor unit,2-picolinic acid as the auxiliary ligand to synthesize organic phosphorescent iridium（Ⅲ）complexes（m-CzFSOPy）₂IrPic and（p-CzFSOPy）₂IrPic,which have the D-A structure.Because of employing rigid ligand frameworks,（p-CzFSOPy）₂IrPic can effective suppress the exciton non-radiative transition from excited state to ground state.The device which use（p-CzFSOPy）₂IrPic as the dopant doped into gust material have achieved the best performance,with a peak quantum efficiency of 5.3%and a peak luminous efficiency of 13.3 cd/A.When the FIrpic and（p-CzFSOPy）₂IrPic as the dopants doped together into host material,the performance of white organic light-emitting device has achieved remarkable improvement,with a peak quantum efficiency of 9.5%and a peak luminous efficiency of 19.2 cd/A.In chapter 3,we have used triphenylamine（TPA）as the electron donor unit,dibenzothiophene-5,5-dioxide as the electron acceptor unit to synthesize organic phosphorescent homoleptic iridium（Ⅲ）complexes（p-FSOPyTPA）₃Ir and（m-FSOPyTPA）₃Ir,which have the D-A structure.Both the homoleptic iridium（Ⅲ）complexes exhibited a good thermal stability,（m-FSOPyTPA）₃Ir exhibited the best thermal stability with a decomposition temperature of 510 ^oC.The solution photoluminescent indicated that the high-lying ¹LC transition state of both homoleptic iridium（Ⅲ）complexes can efficient transfer to low-lying ³MLCT through internal conversion and intersystem crossing,so that reduced the emission of ligand and emitted pure phosphorescence.In chapter 4,we have designed and synthesized small-molecule donor material TPA-Th-BT,TAT-Th-BT,which based on 2,1,3-benzoselenadiazole as the electron acceptor unit,TPA or 10,15-Dihydro-5h-diindolo[3,2-a:3’,2’-c]carbazole（TAT）as the electron donor unit,the acceptor unit and donor unit wereπ-bridged with thiophene.Then,the small-molecule donor material IND-TPA-Th-BT have synthesized through the 3-（dicyanomethlidene）indan-1-one（IND）as the electron-withdrawing substituents to tune the electron donor unit TPA.Because of the electron-withdrawing effect,the value of LUMO energy have decreased remarkably,which not only increase the bandgap from the LUMO of electron donor material to the HOMO of electron acceptor material PC₇₁BM but also increase the absorption region of solar spectrum.The open circuit(V_oc)of IND-TPA-Th have improved to 0.98V,and the device which used IND-TPA-Th-BT as the donor material have the best performance,with a peak power conversion efficiency（PCE）of 1.55%and a short current(J_sc)of 5.47 mA/cm².