Study On The Photoelectric Properties Of LED Based On The Composite System Of Polysulfide Copper Based Nanomaterials And 4,4’,4"-tris(Carbazole-9-yl) Triphenylamine

Quantum dots(QDs)are widely used in display and lighting fields because of their unique optical properties.The traditional QLED devices with heavy metal Cd,which hinders their further commercial application.In recent years,more and more researchers have paid attention to the multinary copper based quantum dots,which is easily synthesized and free of toxic elements.However,the performance of the multinary Cubased QD-LED is low,one of the main reasons is the imbalance of carrier injection and transmission.In order to improve this issue,many methods have been proposed,including the improvement of quantum dot materials and the optimization of device structure.In this paper,we start from the optimization of device structure,and improve the performance of light-emitting diodes based on non-toxic Cu In Zn S/Zn S quantum dots by improving hole injection and blocking electrons.Firstly,in order to solve the problem of hole injection and transport,small molecular material 4,4’,4’’-Tris(carbazole-9-yl)triphenylamine(TCTA)was introduced to prepare QD-LEDs with mixed EML.By finely tuning mass ratios of TCTA to NCs,when the mass ratio of NCs: TCTA is 5:1,the overall performance of the device is best,and the current efficiency reaches 3.22 cd/A.We analyzed the role of TCTA in improving the device performance by testing the photoelectric characteristics of the devices,which provide buffer energy level for hole injection and effective energy transfer for NCs.Then,we applied TCTA to the inverted device,and drew the conclusion that TCTA can also improve the inverted device through the current density brightness voltage curve and current efficiency brightness curve.In order to further balance the carriers in the device,we added polymethyl methacrylate(PMMA)intermediate layer on the basis of mixed EML.From the measurement of the photoelectric performance of the device,the addition of the middle layer not only reduces the electron injection,which is conducive to the electronic and hole balance,but also blocks the direct contact between the zinc oxide surface and the EML,improves the Zn O / EML interface,reduces the quenching of the quantum dots by the surface defects,and improves the efficiency and stability of the device.Through the optimization of electron and hole,the improved device has a lifetime of 5911 s,which is increased by 380%.