Investigation On The High Performance Quantum-dot Light-emitting Diodes Based On The Wettability Improvement

Compared with organic light-emitting diodes(OLED),quantum-dot light-emitting diodes(QLED)have the advantages such as narrow band emission,size-tunable band-gaps,and high photoluminescence quantum efficiency and good stability,so quantum dot LED can be of great potential to be the next generation display and the source of solid-state lighting.Among the above advantages,the greatest advantage the QLED has is that the luminescence purity is very high,so the LED display screen of the quantum dot will have a wider display color gamut,which can show the real color of the nature better,and will improve the visual experience for the human being.In recent years,the research on the structure of quantum dots and electroluminescent devices has made great progress in the performance and stability of the devices.However,the research on the quality of film forming and the performance of devices based on the wettability of fluid is rarely concerned,The material,structure and technology of the devices have direct or indirect connections with the wettability which can not be ignored.It is important to be researched.In this thesis,the wettability based on three kinds of QLED devices is studied.First,in the study of the normal structure QLED,we found that adding appropriate concentration of isopropanol with appropriate annealing temperature can effectively improve the wettability and deposition quality of PEDOT: PSS solution.The roughness of the films decreased obviously,and the crystalline quality of the films increased steadily.In addition,the hole injection efficiency of the PEDOT:PSS layer is enhanced,and the electrical conductivity is increased.Finally,the performance of the QLED device is improved.In the inverted structure QLED,we first studied the material solvent in the hole transport layer,and selected the material solvent that had the smallest influence on quantum dots layer.In addition,the study of the species and residue of the active agent was also researched in keeping the wettability of the hole injection layer PEDOT:PSS.From parameters that improved device performance,we can see that the wettability has a greater impact on the QLED devices that the structure is inverted.In the end,the tandem structure QLED devices are prepared on the basis of the wettability study of the inverted structure.The two sub inverted structures are connected in tandem with the internal connection layer.The current density of the series devices is lower at the same brightness,which is beneficial to the improvement of the stability and service life of the devices.The main findings in this work may offer a practicable strategy for further research,leading to achieve more efficient solution processed QLED.