Preparation Of Electroluminescence Devices Based On Aggregation-induced Emission Materials And Exploration Of New Mechanism

Organic light-emitting diodes?OLEDs?are highly valued in display and lighting applications due to their unique advantages such as light-weight and flexibility,can be made into large-area panel,low power consumption,fast response,and superior luminance.In recent years,owing to the acceleration of its commercialization,how to further improve the performance of OLEDs and how to break through the bottlenecks of blue OLEDs have become research hotspots.Organic light-emitting materials play an important role in the preparation of OLEDs,and aggregation-induced emission?AIE?materials are perfectly used in OLEDs as aggregates due to their distinctive properties.Therefore,the research of OLEDs based on AIE materials have attracted much attention.However,most of the AIE materials are traditional fluorescent materials,and the efficiency of devices based on them is not satisfactory.As a result,the combination of new light-emitting mechanisms and AIE has become a hot spot in the development of organic light-emitting materials.The research of OLEDs based on these new materials will lay the foundation for the subsequent development of materials and the development of OLEDs,and has important guiding significance.To this end,the research content of this thesis is as follows:In chapter two,a large number of materials had been screened and prepared OLEDs based on AIE blue,yellow-green,and red materials respectively.For molecules of different mechanisms and different colors,we have done device structure design individually.By analyzing non-doped and doped devices,we found out the routine methods of high-efficiency device preparation.These findings provide an experimental basis for the subsequent in-depth research of AIE materials with different light-emitting mechanisms,which has the guiding significance.In the third chapter,we researched the organic electroluminescence application of planarized intramolecular charge transfer?PLICT?as a new mechanism had been systematically,and became the first team to fabricate OLEDs based on PLICT materials,demonstrating the great potential of PLICT materials in electroluminescence applications.The blue OLEDs based on two PLICT molecules have achieved maximum external quantum efficiencies(EQE_max)of6.09%and 4.88%,respectively.And successfully fabricated a series of highly efficient orange(EQE_max:28%)and red(EQE_max:18.02%)phosphorescent doped OLEDs when we utilized 26-TPA2P molecules as the host material.After that,two-color hybrid WOLEDs were prepared,and achieved warm-white(EQE_max:17.71%)and pure-white(EQE_max:6.45%)emission,respectively.Additionly,we also prepared the CCT tunable WOLEDs which can simulate natural light,with the EQE_max of 27.69%and the maximum power efficiency(PE_max)of 104.64lm/W,laying the foundation for future lighting applications of OLED.In Chapter 4,a systematic study on the application of OLED based on a kind of new organic light-emitting molecules combining the hybridized local and charge-transfer?HLCT?mechanism with aggregation-enhanced emission?AEE?had been conducted.By carefully adjusting the matching between the electron transport layer and the host material,optimized blue/deep-blue OLEDs are prepared.The doped devices based on this two HLCT molecules both have the EQE_max of over 7%.By utilizing the reverse intersystem crossing?RISC?process of HLCT molecules,we chosed TPA-CNPPI as the sensitizer,successfully realized the mechanism of HLCT-sensitized fluorescent,which broadened the application of HLCT materials.Then we used t Bu CZ-CNPPI as the blue emitter and combination of yellow phosphorescence to fabricate two-color hybrid WOLEDs.Through the optimization of the device structure and a well-designed interlayer called“carrier limiter”,we have achieved highly efficient warm-white(EQE_max:30.15%)and pure-white(EQE_max:20.73%)emission,respectively.And this result is excellent in two-color hybrid WOLED based on AIE/AEE materials as we know.