Study On Controllable Preparation And Photoelectric Properties Of Perovskite Nanomaterials

In recent years,many kinds of nanomaterials have emerged in the field of o-ptoelectronic devices,including quantum dots,nanowires,nanosheets and graphene.However,due to many constraints such as high cost,large size,and difficult inte--gration,the large-scale application of traditional semiconductor nanomaterial devic-es still faces challenges.Metal halide perovskite nanomaterials have received exte-nsive attention from researchers due to their high performance,low cost and rich material composition.The first job was to prepare bismuth-lead halide perovskite nanocrystals and study their optoelectronic properties.In this paper,the microcrystalline structure of bismuth-lead halide perovskite（CsPbX₃,X=Cl,Br,I）was prepared by CVD.Thes-e perovskite nanocrystals produce intense blue、green、and red fluorescence under excitation of 403 nm light,indicating that their band gaps can be designed and cover the entire visible range.Based on the different band gap compositions of in organic bismuth-lead halide perovskite nanocrystals,wide-band light absorbing and emitting devices can be obtained.An optically pumped red-green-blue echo wall mode laser based on these nanocrystal compositions was successfully implemented at room temperature.Further,a white light-emitting chip having high luminance can be prepared by using these metal halide perovskite nanocrystals grown on sap phire.All of these results clearly provide a viable path for the design of red、gre-en and blue lasers and white light emitters,with potential applications in full col-or displays and photonic devices.The second job was to prepare a large-area high-quality bismuth-lead halide perovskite single crystal film and study its optical properties.Since the perovskite single crystal film has a lateral dimension of several tens of micrometers and a thickness of several tens to several hundreds of nanometers on a macroscopic scal-e,it can be easily integrated with other existing electronic materials in a scalable manner,in a designable configuration.Stacking different perovskite single crystal f-ilms can create complex devices that cannot be implemented in nanocrystals or n-anowires.In this paper,an effective CVD method was used to successfully grow a large-area high-quality perovskite single crystal thin film with excellent morphol-ogy on a single substrate and its optical properties were studied.The prepared na-nocrystalline film has a single crystal side length of about 10 micros and a thick-nes of about several hundred nanometers.Our research on the properties of perovs-kite single crystal films shows that it has potential commercial application value.The third job is to prepare tin-catalyzed cadmium sulfide cadmium nanowires for use in optical waveguides and room temperature high quality nanolasers.Due to its high refractive index,nanowires can serve as both active gain materials and optical waveguide materials,and therefore have broad prospects for integrated pho t-onic applications.In order to achieve the growth of high-quality tin-catalyzed ca d-mium sulfide nanowires,we have developed a simple two-step CVD method wh i-ch is easy to operate,has strong controllability,and has a high quality product.Microstructural characterization indicates that these lines are high quality crystallin-e nanostructures.Local photoluminescence studies of these nanostructures show a typical band edge emission at 656 nm with a full width at half maximum of 22.3nm.Measurements of the optical waveguide along a single nanowire show that a-fter transmission of light at a wavelength of 102μm,the output optical signal e-xhibits a rapid linear downward trend with a maximum red offset of approximate-ly 109 MeV.This apparent red shift is caused by the strong band tail absorption during light transmission.In addition,based on these unique nanowire structures,optically pumped nanolasers were successfully fabricated at room temperature,furt-her demonstrating that pump power intensity can facilitate the transition from spo-ntaneous emission to stimulated emission.This work proposes a simple method o fpreparing high quality nanowires and may be used to fabricate waveguides and i n-tegrated photonic devices.