TiN Nanoparticles Were Prepared By PS Template To Enhance The Performance Of Cs₂AgBiBr₆ Perovskite Photodetector

Due to their unique optical and electrical properties,such as high carrier mobility,high photoluminescence efficiency,high extinction coefficient and adjustable band gap,perovskite materials have become a research hotspot in the field of photodetectors.Current metal-halogen perovskite materials for photovoltaic and detection applications contain lead,and the toxicity of lead to some extent hindrance the large-scale industrial application of perovskite photodetectors.Lead-free double perovskite material Cs₂Ag Bi Br₆ not only solves the problem of lead toxicity,but also has excellent photoelectric properties,which can be used to prepare environment-friendly photodetectors.However,Cs₂Ag Bi Br₆ has a wide band gap and can only work in the ultraviolet band,and its detection rate in the ultraviolet band is two orders of magnitude lower than that of organic-inorganic hybrid lead halide perovskite photodetectors,which largely hinds its application.A large number of studies have shown that the surface plasmon effect based on metal or nonmetal nanostructures can improve the detection rate and broaden the detection range of photodetectors through reasonable design,the Ti N work function is 5.05 e V,and the Fermi level of Cs₂Ag Bi Br₆ material is 5.16 e V.The Ti N nanostructure contacts Cs₂Ag Bi Br₆ material to form schottky heterojunction.The SPP effect of Ti N nanostructure is used to stimulate the hot hole,and the hot hole crosses the Schottky barrier into Ti N.Thus enhancing the performance of photodetectors.In this work,we intend to use the surface plasmon effect of Ti N nanoparticles to expand the detection range of Cs₂Ag Bi Br₆photodetector to the near-infrared band.In order to achieve low-cost preparation of nanostructures,Ti N nanoparticles were prepared by using single-layer polystyrene（PS）spheres as masks and applied to Cs₂Ag Bi Br₆photodetectors.The main work is as follows:（1）Fabrication of Ti N nanoparticles array.Firstly,a single layer of densely packed PS nanoparticles was arranged on a glass substrate,and then the diameter of PS nanospheres was reduced by reactive ion etching（RIE）method,so as to obtain a non-densely packed and ordered distribution of PS nanoparticles template.Based on the template,Ti N with a certain thickness was sputtered and PS nanoparticles were cleaned to obtain Ti N nanoparticles array.Firstly,hexagonal densely packed PS nanospheres with diameters of 800 nm,500 nm,300 nm and 100nm were successfully prepared by optimizing the arrangement process of the spheres.Then,the non-dense PS nanosphere template was obtained by reducing the diameter of the nanosphere by 50-100 nm by optimizing the etching conditions.Finally,using PS nanospheres with diameters of 700 nm and 50 nm as templates,Ti N nanoarrays were successfully prepared by magnetron sputtering.（2）Fabrication of ultraviolet and near-infrared photoelectric detectors based on Cs₂Ag Bi Br₆.Firstly,a high quality Cs₂Ag Bi Br₆ film was prepared by two-step spin coating method.Then,a metal-semiconductor-metal（MSM）photodetector was prepared based on the film.The light-dark current ratio of the standard device reached 1.26×10⁴.Then,we prepared the Cs₂Ag Bi Br₆ photodetector modified by Ti N nanoparticle array and optimized its photoelectric performance.Finally,the light-dark current ratio of the device was 5.5 times in the band of 1550 nm,and the detection range was widened from 300-500 nm to 300-1550nm.