Research On The Optimization Of New Organic Silicon Materials For The Performance Of Perovskite Light-emitting Diodes(PeLEDs)

Organic-inorganic hybrid perovskite is a semiconductor material with special optoelectronic properties.It has the advantages of low raw material cost,good solubility,narrow emission peak width and adjustable band gap.In the past ten years,perovskite materials have attracted widespread attention from scientific researchers at home and abroad because of their outstanding application prospects in the fields of solar cells and photodetectors.However,the performance of the light-emitting Diodes（LEDs）prepared with perovskite as the light-emitting layer is still lower than the solar cells.This is mainly due to the lower exciton binding energy,which makes the excitons easier to dissociate.At the same time,the surface of the perovskite film prepared by the solution method is prone to defects,which can cause non-radiative recombination by quenching excitons and trapping charges,thereby reducing the performance of perovskite light-emitting diodes（Pe LEDs）.Therefore,methods such as improving the performance of the perovskite film and reducing the defect density are the keys to effectively improving the performance of Pe LEDs.In this paper,two kinds of amphiphilic silicone copolymer passivators with linear and comb structures were designed and prepared.From the perspective of passivator engineering,the surface coverage of perovskite film,crystal crystallinity and fluorescence intensity are improved by passivating agent to passivate the grain defects of perovskite film,so as to obtain Pe LEDs with good photoelectric performance.The main work contents are as follows:1.Preparation of ABA linear structure terminal quaternary ammonium salt polyvinyl alcohol modified organosiloxane copolymer(Si₁₄-PEG₁₄-QAC)passivation agent and its application in Pe LEDs.As a passivating agent,Si₁₄-PEG₁₄-QAC was doped into the quasi two-dimensional perovskite precursor solution in a certain proportion,and then high quality perovskite films were prepared by one-step spin coating method.Scanning electron microscope（SEM）results show that Si₁₄-PEG₁₄-QAC can effectively improve the surface morphology and surface coverage of perovskite film,X-ray diffraction（XRD）and transient fluorescence spectrum results show that Si₁₄-PEG₁₄-QAC can restrain the growth of perovskite grain and thus reduce the size of perovskite grain.The time-resolved photoluminescence（TRPL）of the prepared perovskite film can reach 102.5 ns,which is 1.57 times higher than that of the perovskite film without passivating agent,indicating that Si₁₄-PEG₁₄-QAC can effectively passivate the defects on the surface of the perovskite film,nonradiative recombination of inhibited excitons.Based on this perovskite film,high-performance green Pe LEDs were prepared.The maximum current efficiency（Luminance Efficiency,LE）of the device was increased from 3.32to 17.32 cd/A,and the maximum external quantum efficiency（External Quantum Efficiency,EQE）also increased from 0.86%to 4.5%.2.Preparation of amphiphilic comb-like structure of propylamino-modified organosiloxane copolymer[Si₉-(Si _Pro-QAC)₃]passivation agent and its optimization of perovskite film morphology.The prepared Si₉-(Si _Pro-QAC)₃passivation agent was prepared into toluene,and the antisolvent was used to wash and dissolve the surface before rapid crystallization and film formation to improve the film morphology and reduce defects.The results show that the Si₉-(Si _Pro-QAC)₃dissolved in toluene can fill the defects,increase the coverage,and promote the crystal regularity of the perovskite.The fluorescence quantum yield（PLQY）of the prepared perovskite film increased from 0.14%to 14.86%,and the TRPL reached 56 ns,which was 1.37 higher than pure perovskite film.It can effectively suppress the photoluminescence quenching and avoid the non-radiative recombination loss caused by defects.In conclusion,the linear and comb-like amphiphilic silicone copolymer passivator was introduced into the perovskite luminescent layer in this paper,and the perovskite film with low defects was prepared,which effectively improved the efficiency of perovskite luminescent devices and provided an effective method for the improvement of device performance.