Design,Synthesis And Characterization Of Light Emitting Material Based On Naphthalimide

Organic light-emitting materials have been widely applied in organic light emitting diodes(OLED),fluorescent sensors,photovoltaic cells and clinical therapy due to their varied structure,easy-modification and low cost.Among these applications,what relates to the public life most closely is OLED screen.With the continuous popularization and development of mobile smart devices represented by smart phones,the small-sized screens that they carry need fine,bright-colored and power-saving display technology.With its excellent display effect,OLED screen is the best choice with no doubt.It satisfied the consumers'requirement of wide color gamut,high contrast ratio and low power consumption.Hence,the preparation of new high efficiency organic light emitting materials is significant in expanding the correlative system and its application.As one of the most versatile fluorophore unit,naphthalimide has been explored extensively in various real-world applications such as cell imaging,drug delivery and biochemical sensing.This ascribes to their accepting capacity and high quantum yields.Besides,the aromatic core along with the N-imide site can be modified through easy and cost-effective synthetic route that allows for varieties of structural units and functional groups to be fused.This thesis focuses on the moieties of naphthalimide and carried out scientific research as follows:In chapter 2,we synthesized two novel D-A structure fluorescent molecules NI-TPA and NICN-TPA.The naphthalimide's 4-position are modified with triphenylamine donor,N-position with phenyl and 4-cyanophenyl,respectively.We systematically explored the effect of various N-position modification on its optoelectronicpropertiesthroughelaboratecharacterizationsofthermal,photophysical and electrochemical properties.The turn-on voltages of non-doped devices based on NI-TPA and NICN-TPA are 3.0 V and 3.1 V,respectively;the emission peaks located at 583 nm and 609 nm,respectively;the external quantum efficiencies are 4.75%and 2.06%,respectively;the maximum luminance of the device based on NI-TPA reached 63027 cd/m~2,which is among the highest values of the orange-red OLEDs reported recently.The doped devices using CBP as host material showed higher external quantum efficiencies in comparison to the non-doped devices,which reached 6.46%and 6.32%,respectively.The emission peaks located at556 nm and 552 nm,respectively.In chapter 3,we use triphenylamine and N-phenyl-9,9-dimethylacridine as donor cores,N-phenyl-1,8-naphthalimide as acceptors to gain two A-D-A structure fluorescent molecules 2NI-TPA and 2NI-DMAC.In contrast to NI-TPA in the last chapter,the thermal stability of both materials increased apparently;the non-doped devices of 2NI-TPA and 2NI-DMAC have a bathochromic emission peak at 596 nm and 601 nm,respectively;the external quantum efficiencies slightly decrease to4.74%and 1.35%;the turn-on voltages are 3.2 V and 3.4 V,respectively;the maximum luminance of the device based on 2NI-TPA reached 68837 cd/m~2,which is among the highest values of the orange-red OLEDs reported recently.2NI-TPA and2NI-DMAC showed higher external quantum efficiencies in doped devices,which is5.12%and 5.31%,respectively.