Preparation Of Quantum Dot/polymer Composite Films By Fiber Liquid Bridge Method And Fabrication Of Large-area QLEDs

Colloidal Quantum dots(QDs)are the core materials of Quantum dot Light-Emitting Diode(QLED)with high fluorescence Quantum yield,narrow emission spectrum,adjustable emission peak position and long life.QLED devices are expected to become the mainstream of the next generation of lighting and display technology.The solution method is low cost,large area of main method of the high-performance QLED devices,including spin,inkjet printing,transfer printing,ink-jet printing is the most development potential of large area of preparation technology,but at the moment on the film quality and device manufacturing process also there is a big problem,and most of the core technology and equipment by foreign monopoly.In view of the current problem of large-area preparation of high-quality QLED devices,the research group realized the efficient preparation of large-area uniform QDs films and constructed high-performance large-area QLED devices based on the developed two-dimensional fiber liquid bridge system.However,in the development of QLED devices,the structural stability of QDs film is the key to limit the long-term stability of devices.How to improve the stability of QDs films is an important problem.Here,inspired by the combination of polymer and QDs film to construct photoluminescent film,based on the two-dimensional fiber liquid bridge system,we added polymer to the prepared large-area film to form QDs/polymer composite film,thus improving the stability of the film.It provides a new research idea and technical means for improving the long-term stability of devices and constructing flexible devices.In this paper,based on the fiber liquid bridge technology,aiming at the stability of QDs film,the QDs/polymer composite film structure was prepared,and the regulatory effect of polymer type on fiber liquid bridge printed QDs film was studied in depth,and the effect of polymer content in the film on its photoelectric properties was analyzed.By optimizing the preparation parameters of QDs/polymer composite film,the stable large-area uniform QDs composite film structure was obtained,which further improved the stability of QLED devices.Meanwhile,large-area and high-stability flexible and white QLED devices were prepared.The main research contents of this paper are as follows:1.Preparation of quantum dot/polymer composite filmsFirstly,the effects of single and binary solvents on QDs film quality were studied.The best QDs film was obtained by chloroform and n-octane binary solvents.Secondly,on the basis of binary solvent and polymer PDMS,the proportion of PDMS in QDs composite solution,printing speed and binary solvent mixing ratio were studied to achieve the preparation of high-quality QDs/polymer composite film.2.Study on the structural stability of QDs/polymer composite films and its application in QLED devicesFirstly,the interaction between PDMS and QDs in the process of fiber liquid bridge printing film was studied.By regulating the content of PDMS in the quantum dot/polymer composite film,the Forster resonance energy transfer between quantum dots was inhibited while maintaining the stability of the film,and the photoelectric performance of the film in QLED devices was further improved.Secondly,the effects of different solvents such as water and acetone,natural environment and temperature on the structural stability of quantum dot/polymer composite films were studied.A flexible monochrome QLED device was constructed based on stable QDs/PDMS composite film,and a high-performance white QLED device was constructed by using PDMS to inhibit the resonance energy transfer between multicolor QDs in the film.