Preparation And Applications Of Soluble Donor-Acceptor Molecules Containing Multiple Carbazole Arms

In this thesis,a series of D-A functional materials containing multiple carbazole arms were designed and synthesized,including"Z"typed carbazol-pyridine host materials and carbazol-diphenyl sulfone luminescent materials.The host materials show high triplet energy level,good thermal stability,balanced carrier transport capacity and good film-forming property,while the luminescent materials possess high PLQY and good thermal stability,and all are applied to organic electroluminescent devices,and the photoelectric properties are evaluated and analyzed with the details are listed as follow,?1?Six phosphorescent host materials,named 3PymCZ,3PyoCz,3PypCz,4PymCZ,4PyoCz,4PypCz were synthesized.Firstly,we introduce the carbazole group to the intermediate benzene ring through the Ullman reaction,and then we introduce the pyridine group through two-step Suzuki coupling reactions.These materials are used as the host materials,and be doped with the corresponding guest materials through simple solution process method.The performance of 3PyoCz is the best among these six materials with the maximum current efficiency of 16.71 cd/A for the blue phosphorescent devices doped with Firpic guest.And the orange phosphorescent devices doped with Ir?bt?₂acac guest also reached high performace with a maximum current efficiency of 24.77 cd/A and a maximum brightness of 36,917 cd/m².While the green phosphorescent devices doped with Ir?ppy?₂acac guest exihibits high efficiency of 27.02 cd/A.Further more,the device performances were further enhanced to 24.1 and 45.2 cd/A for the blue and green phosphorescent devices,respectively,through adding a small amount of TAPC into the 3PyoCz host material.?2?We utilized 1,3-dibromo-5,5-dimethylhydantoin to brominated diphenyl sulfone,and yielded two different intermediates,which were coupled with carbazole derivatives through Ullman reaction and produced two new D-A luminescent TADF materials,3CzDPS and 4CzDPS.The photophysical properties,electrochemical properties,and thermal behaviours were systematically characterized,and the applications in OLEDs were also discussed.The preliminary results show that this kind of materials have good optical irradiation characteristics,suitable HOMO/LUMO energy levels,and good chemical compatibility.We demonstrated that 3CzDPS is a good luminescent material with a maximum current efficiency of 8.45cd/A and an external quantum efficiency of 4.03%in a blue OLEDs fabricated by solution processing.