Optimization Of Quasi-two-dimensional Perovskite Light-emitting Diodes

(A₁)₂（A₂）_n-1Pb_nX_3n+1quasi two-dimensional perovskite material with quantum well structure is different from three-dimensional perovskite and two-dimensional perovskite,and shows good stability and higher light-emitting quantum efficiency,promising a potential material for light-emitting diode.However,there are still some problems with the perovskite films prepared by solution processing,such as uneven n phase distribution,the rough surface of perovskite film and the increase of surface defects.These adverse factors lead to the low luminous efficiency of quasi-two-dimensional perovskite light-emitting diodes,and the luminous efficiency drops rapidly at high current densities.Optimizing the materials and devices of quasi-two-dimensional perovskite light-emitting is an urgent problem which need us to solve.In this paper,we aim at the problem of quasi-two-dimensional perovskite light-emitting diode.We study the dissociation of exciton of quasi-two-dimensional perovskite light-emitting diode under the high electric-field,and use organic cationic salt solution to modify the surface of quasi-two-dimensional perovskite films by solution post-treatment.We try to improve the phase distribution and purity quotient of quasi-two-dimensional perovskite films.These approaches are developed to improve the performance of quasi-two-dimensional Pe LEDs.We also try to prepare the quasi two-2D perovskite light-emitting layer by the reaction preparation method of organic ions and 2D perovskite to improve the phase distribution and morphology of the light-emitting layer.（1）Through to measure the electric-field modulated photoluminescence,we study the the electric field induction quenching of excitons.By comparing the changes in luminescence intensity under different electric fields and the lifetime changes of the excited states,it is proved that the exciton ionization of quasi-two-dimensional perovskite materials mainly occurs in the（A₁）₂（A₂）_n-1Pb_nX_3n+1phase during the funnel energy transfer process,which is one of the main reasons for the efficiency roll-off phenomenon of the devices.In this paper,PEABr and N-BABR were used for post-treatment of（PEA）₂FA₂Pb₃Br₁₀quasi-two-dimensional perovskite film,using the solution post-treatment method,effectively improve the perovskite quantum well structure,reduce exciton dissociation under high voltage.（2）The quasi-two-dimensional perovskite film quantum well structure was improved by solution post-treatment to improve the luminescence efficiency of the device.PEABr and N-BABR were used for post-treatment of（PEA）₂FA₂Pb₃Br₁₀quasi-two-dimensional perovskite film,using the solution post-treatment method,improve quantum well structure and phase distribution.The study shows that the post-treatment of organic ionic salt solution can improve the quality of（PEA）₂FA₂Pb₃Br₁₀film,which can improve the turn on voltage,brightness and current efficiency of the device.After treatment,the film surface is more smooth,and the defect density is significantly reduced.The two salts solutions can react with the 3D phase of the film and form a quasi-two-dimensional phase,thus improving the structure of the quantum well.（3）A quasi-2D perovskite light-emitting diode was prepared by ion reaction combined with inkjet printing technology.The MABr solution as ink was printed on PEA₂Pb Br₄two-dimensional perovskite film,using both reactions were quasi two-dimensional perovskite leds.The luminance of the device can reach 7622cd/m².The preparation of quasi two-dimensional perovskite films and light-emitting devices by small ion salt solution and 2D perovskite reaction is proved for the first time,which provides a method for the preparation of patterned quasi two-dimensional perovskite devices by inkjet printing.