Synthesis And Properties Of Small Molecule Optoelectronic Materials With Quinolinone Derivatives As Acceptors

Organic Light Emitting Diodes(OLEDs)have shown great potential in display and lighting applications due to their really dark,fast response time,superior chromaticity,flexibility and energy conservation.Organic small-molecule compounds with donor-acceptor(D-A)type are widely used as fluorescent emitters due to their good intermolecular or intramolecular charge transfer properties.In this paper,four series of D-A type small-molecule organic optoelectronic materials were designed and synthesized by using quinolinone and quinoline-like derivatives as acceptor and triphenylamine as donor.Their thermal stability,electrochemical and photophysical properties were systematically studied.The main research contents are as follows:First,five target compounds were synthesized based on piperidinoquinolinone derivatives as the acceptor.It was found that the distribution of the highest occupied molecular orbital(HOMO)and the lowest unoccupied molecular orbital(LUMO)also changed with the change of the relative position of the donors and the receptors.The emission peak of the photoluminescence(PL)spectrum in solid films showed blue emission between 409-456 nm.The fine structure of the emission spectrum proves that the compounds have local excitation(LE)property in excited state;the solvation effect indicates that these compounds have intramolecular charge transfer(ICT)characteristic.The interaction of two properties is beneficial to OLED devices achieve high luminous efficiency;Secondly,five D-A type small-molecule compounds were synthesized based on tetrahydropyrroloquinolinone derivatives as the acceptor.It was found that these target compounds have good thermal stability,which is beneficial to the emission layer of OLED devices to maintain good morphological stability during operation.Their emission peaks in the film are all at 431-460 nm,showing good blue emission characteristics.The various relative positions of acceptor and donor can effectively adjust the molecular orbitals distribution,which can make the energy level of the emission layer match that of the transmission layer to balance the carriers of the whole device;Subsequently,five target molecules were synthesized based on dihydropyrroloquinolinone derivatives as acceptor,it was found that the larger conjugated structure of these compounds and the propeller structure of triphenylamine caused a larger twist between the donor and acceptor.The larger distortion leads to a higher thermal decomposition temperature,and the good thermal stability is important for the manufacture of OLED devices.The PL spectrum was measured in the solid thin film,and the emission peaks are between 438-487 nm,which have the potential as blue luminescent materials;Finally,a series of small-molecule blue luminescent materials were designed and synthesized using quinoline-like compound as acceptor.By introducing appropriate linkers,the donor-acceptor distance and electronic property were adjusted,and finally high-efficiency fluorescence was achieved.Using these compounds as blue emitters in non-doped OLEDs,all devices exhibited stable blue emission with excellent electroluminescence(EL)performance.In addition,a hybrid white organic lightemitting diode(WOLED)was prepared by using these compounds as double blue light-emitting layer and host material doped with phosphorescent dyes.The maximum current efficiency and external quantum efficiency of the device were 67.6 cd/A and24.3%,respectively.