| The inkjet printing technology has the characteristics of high material utilization rate,large-area,low-cost fabrication features,which is widely used in the field of pixelated light-emitting display devices.However,traditional inkjet printing is difficult to meet the needs of high-resolution display manufacturing due to its low resolution and poor quality of film.Herein,this dissertation proposes the use of electrohydrodynamic(EHD)printing technology to achieve high-resolution luminescent pattern deposition,and cooperates with comprehensive optimization of functional ink material characteristics to adjust the shape of the printed film.Finally,pixelated quantum dot light-emitting devices(QLEDs)were fabricated based on high-resolution EHD printing and high-quality light-emitting film.These results indicate that the EHD printing has great potential in the preparation of high-resolution pixelated display.The main work of this paper includes:Firstly,the study on the drop on demand(DOD)of EHD printing was proceed.In the paper,the experimental method was applied to systematically research the influence of the process parameters(peak voltage,frequency and duty cycle)and the solution characteristics(conductivity)on the droplet volume,and the result found that the printing rule of the duty cycle of the pulse voltage had changed due to the difference in solution conductivity.Based on the comprehensive optimization of the printing process conditions,the preparation of high-resolution quantum dot(QD)arrays and perovskite arrays was realized,which laid the solid foundation for the preparation of pixelated electroluminescent devices.Secondly,coffee-ring-free film was obtained.Based on the characteristics of perovskite and QD functional inks,the DOD process of EHD printing was comprehensively optimized,and the influence of viscosity and mixed solvent on the coffee-ring phenomenon in the droplet drying process were studied.For the ionic perovskite solution,adding long-chain polymer to increase the viscosity of the solution was combined with the high viscosity printing characteristics of EHD printing to achieve the dual control of morphology and crystal.Moreover,complex full-color perovskite patterns with high-quality were prepared on the flexible substrates.Next,for the colloidal QDs solution,by studying the inhibition rule of the mixed solvent ratio on the coffee-ring phenomenon,the preparation of high-resolution,flat QD thin films was achieved.Thirdly,pixelated QLEDs were prepared.The materials / manufacture methods of each functional layer and EHD printing process were optimized comprehensively to achieve the preparation of QD films with high-resolutions,solving the problems of mutual dissolution of each functional layer and mutual contamination between adjacent pixels.The structure of the inverted QLEDs is designed first,and then Zn O was manufactured by magnetron sputtering,pixel definition layer was prepared by photolithography,QD light-emitting layer was printed,hole transport / injection layer and metal anode were sequentially deposited.Finally,the device was prepared by EHD printing,and its photoelectric performance was characterized. |
