Preparation And Investigation Of High Efficient Organic Luminescent Materials With D-A Structure

The rapid development of the economy depends on the continuous supply of energy.In the future,fossil energy will eventually be exhausted.Scientists have taken precautions to adopt new ways of energy conservation and utilization,seek new sustainable energy sources such as wind energy,solar energy,tides,etc.On the one hand,the development of more energy-efficient materials,such as the use of more efficient materials in the display of lighting.When the molecules were externally excited,it will transition from the ground state to the excited state of the high energy level,and a part of the energy will be released as a radiation transition.A new generation of organic light-emitting diode(OLED)can convert electrical energy into Light energy,with low energy requirements,wide viewing angle,high resolution,active illumination,color saturation,bendability,all solid state and low drive voltage.So far,organic light-emitting diodes have been industrialized as lighting devices,smart phones.Portable displays even large TV displays.They were considered to be the mainstream of future lighting and flat panel display technologiesThermally activated delayed fluorescence(TADF)materials,room-temperature phosphorescence(RTP)and Aggregation-induced emission(AIE)were studied in the multi-channel properties of organic light-emitting materials.Applied research on luminescence.The main contents and innovations of this paper are as follows:(1)The TADF polymer P1 reported in the previous period is a guest material,and the improvement of TADF performance in OLED devices doped with different host materials is studied.Little delayed fluorescence was observed in the pure film or host material 9-(4-tert-Butylphenyl)-3,6-bis(triphenylsilyl)-9H-carbazole(CzSi)of P1.The maximum external quantum efficiency(EQE)of devices using 9,9'-(1,3-Phenylene)bis-9H-carbazole(mCP)as the host material is 4.26%,while the EQE of devices based on P1 pure film is only 0.87%.The results show that in devices with mCP,about 31%internal quantum efficiency(IQE)can be obtained,with delayed fluorescence emission accounting for 74%,much higher than devices with P1 pure film(about 14%delayed emission).For devices based on the 2,4,6-tris[3-(diphenylphosphinyl)phenyl]-1,3,5-Triazine(PO-T2T):P1 mixture,the delayed emission in the IQE is approximately 90%.The results clearly demonstrate that the matrix material is critical for the emission of delayed fluorescence in an effective TADF polymer.(2)In the triplet excited state radiation transition channel,we designed and synthesized two room temperature phosphorescent materials M1 and M2,which were compared with the previous work MO.It was found by density functional theory(DFT)calculation that the energy gap between the singlet excited state and the triplet excited state increases gradually with the decrease of the number of benzene rings in the designed room temperature phosphorescence(RTP)molecular structure,and the energy gap of all three was greater than 0.03 eV,indicating that the molecule With the limited ability of reverse intersystem crossing(RISC),the energy of triplet excited state can be more utilized in phosphorescence emission,which limits the activity of intersystem crossing(ISC)after the energy gap was further increased,resulting in lower concentration of triplet excitons and shorter lifetimes of M2.The single crystal is used to resolve the molecular packing method,and the materials were applied in its cell therapy and has certain effects,which provide a guiding significance for the room temperature phosphorescent material in the diagnosis and treatment of cancer cells.(3)A high-efficiency aggregation-inducing luminescent fluorescent material with 1,1,2,2-tetraphenylethene(TPE)structure was designed and synthesized.In the experiment,the molecule was subjected to aggregation-induced luminescence modification by introducing a TPE structure into the aggregation caused quenching(ACQ)molecule F1 have high photoluminescence efficiency.After the introduction of the TPE structure in the ACQ molecule F1,the molecules F3,F4,and F5 have high efficiency of fluorescence emission in the solid state.As the degree of molecular distortion and the increase in molecular weight and structural rigidity,the fluorescence emission shows a significant red shift.