The Design,Synthesis And Device Performance Of Novel Organic Electroluminescent Materials

In recent years,in the field of light-emitting diode,organic light-emitting materials play an increasingly important role,and the organic light-emitting diode(OLED)has been commercialized.In R,G,B three kinds of colors,red and green for organic material,whatever in the luminescent efficiency or stability,have reached the mature stage.On the contrary,blue light organic material is not so good.Therefore,this paper focuses on the organic small blue molecule and thermal activated delayed fluorescence(TADF)materials and their performance of devices.First of all,we have studied 9,9-dimethyl acridine and dicyanobenzene or benzophenone as building units of TADF materials,namely 3,5-DAcr-BIPN and 3,5-DAcr-BP.These two kinds of materials,via the meta-position connection,dicyanobenzene or benzophenone electron acceptor unit and two 9,9-dimethyl acridine electron donor units were respectively connected in the 1,3,5 position of benzene ring.Through the thermal stability test,two compounds have the basic conditions for evaporation,stable solid films can be formed.3,5-DAcr-BIPN as guest material,doped in the main material m CP,together as light-emitting layer of device A.The maximum external quantum efficiency(EQEmax)of device A is up to 16.5%.In the mean time,3,5-DAcr-BP as guest material,doped in the main material m CP,togethor as light-emitting layer of device B.The EQEmax of device B is up to 9.5%.The luminescent performance of device A is better than device B,the main reason is due to the stronger electron-withdrawing ability of dicyanobenzene than benzophenone.In addition,during the range of luminance,CIEx,y only changes from(0.22,0.40)to(0.22,0.39)for device A,CIEx,y only changes from(0.36 0.56)to(0.35,0.56)for device B.Secondly,we also have developed a series of benzimidazole and three aniline as building units for blue fluorescence organic small molecules were developed.Namely BI-A-TPA,BI-B-TPA,BI-C-TPA and BI-D-TPA.These four materials,three aniline as electron donor unit and benzimidazole as electron acceptor unit,by changing the connection way of phenyl bridge between benzimidazole and three aniline,to regulate the intramolecular charge transfer interaction strength,ultimately prevent the bathochromic shift of luminescent materials.Using BI-A-TPA as a light-emitting layer to make device A,EQEmax is up to 2.93%,the maximum current efficiency(CEmax)is up to 1.11cd/A,the maximum power efficiency(PEmax)is up to 1.16lm/w.Using BI-B-TPA as a light-emitting layer to make device B,EQEmax is up to 1.34%,CEmax is up to 0.68cd/A,PEmax is up to 0.66lm/w.And using BI-C-TPA as light-emitting layer to make device C,EQEmax is up to 0.64%,CEmax is up to 0.45cd/A,PEmax is up to 0.32lm/w.Using BI-D-TPA as ight-emitting layer to make device D,EQEmax is up to 2.00%,CEmax is up to 1.15cd/A,PEmax is up to 1.17lm/w.