| Due to the characteristics of simple synthesis,high photoluminescence quantum yield(PLQY),and high purity of emission color,perovskite quantum dots have great potential in the field of display.Inkjet printing technology is an effective solution to realize quantum dot display.Research on perovskite quantum dot ink suitable for inkjet printing,film drying process,full-color integration technology and device interface modification will help realize full-color perovskite quantum dot display and promote the development of perovskite quantum dot display.This paper focused on the realization of red,green and blue three-color perovskite quantum dot light-emitting diodes based on inkjet printing technology.Researches on ink preparation,film formation process,and device interface modification improved the film formation quality of inkjet printing perovskite quantum dots,improved device efficiency,and realized red,green,and blue three-color integration.The specific research results are as follows:First,the preparation method of green perovskite quantum dots was studied,and a method of adding a small amount of oleylamine in the purification process was proposed,which improved the storage stability of the solution,and improved the PLQY and device performance of perovskite quantum dots.Green perovskite quantum dots were synthesized at room temperature.The ink was configured with a mixed solvent of n-octane and dodecane,and the capillary flow and Marangoni flow were balanced during the droplet drying process when the volume ratio of n-octane and dodecane was optimized to be 4:6.A flat film was obtained,and a green light perovskite quantum dot pixel array device was fabricated by combining inkjet printing technology,with a maximum EQE of 2.8% and a resolution of 120 PPI.The stable red perovskite quantum dots were synthesized by Sr,Zn doping method,and the effect of interface modification on the carrier transport and performance of the device was studied.It was proposed to introduce the interface modification layer OAm Br into the lightemitting device to passivate the surface defects of the perovskite quantum dot film,which not only improved the PLQY of the film,but also balanced the carrier transport of the device and improves the device efficiency.The maximum EQE of red perovskite quantum dot devices fabricated by spin coating was 16.5%.The polymer blending method was used to prepare the red perovskite quantum dot ink,which was used in the inkjet printing technology to prepare the pixel film,and the "coffee ring" phenomenon was suppressed by delaying the drying time and weakening the aggregation of quantum dots with capillary flow towards the edge of the droplet.A red-emitting Pe QDs array device with uniform pixel emission was obtained,and its maximum EQE was 9.6%.Using the method of solid-phase ion exchange,OAm Cl and PEAI were used as ion exchange media to exchange ions with green perovskite quantum dots,and a multi-band perovskite quantum dot device from blue to red light was prepared.The effects of ethanol,isopropanol and n-butanol on the morphology,structure and optical properties of ionexchanged films were compared,among them,the isopropanol ion-exchanged film with the highest PLQY and the best device performance.Using isopropanol as the ion exchange solvent,the electroluminesence spectra of the blue to red devices were located at 468 nm,481 nm,493 nm,518 nm,604 nm,618 nm,630 nm,and the maximum EQEs are 1.9%,4.6%,6.6%,4.4%,4.2%,8.7%,7.1%,respectively.Finally,in order to realize full-color perovskite quantum dot devices,inkjet printing technology combined with solid phase ion exchange method was used to print PEAI and OAm Cl ink respectively,and ion exchange occurred with the underlayer green perovskite quantum dot films to obtain red and blue perovskite quantum dot films.Different bands of perovskite quantum dot films can be obtained by adjusting the concentration of PEAI/OAm Cl ink.The maximum current efficiency of full-color perovskite quantum dot devices prepared by this method was 0.78 cd/A. |
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