Photoluminescence Modulation And Large-area Preparation Of Two-dimensional NdOCl Crystal

Photoluminescent materials have a wide range of applications in all solid-state compact lasers,three-dimensional displays,infrared quantum counters,temperature detectors,fluorescent probes for biomolecules,optical storage and so on.Therefore,the development of high-performance,adjustable photoluminescent materials has important practical significance.Rare earth materials exhibit special properties due to their unique electronic structure and have particular advantages in photoluminescence applications.At present,the luminescence research of rare earth materials is mostly based on zero-dimensional quantum dots,while the research of two-dimensional structure rare earth materials is rarely reported.Compared with zero-dimensional quantum dot materials,two-dimensional materials are more sensitive to the modulation of the environment and external fields,and in principle can produce more significant luminescence and modulated properties.Therefore,it is necessary to carry out systematic research on the controllable preparation and photoluminescence properties of two-dimensional rare earth materials.NdOCl is a tetragonal perovskite-type material,which contains the rare earth element neodymium(Nd).It has excellent temperature and atmospheric stability,which considered as an ideal candidate material for photoluminescence modulation in two-dimensional rare earth materials.In this paper,the photoluminescence properties of two-dimensional NdOCl nanosheets were systematically studied by various methods,and large-area two-dimensional NdOCl films were prepared by vapor deposition method assisted by confined space.The specific research content is as follows:(1)Modulation of the photoluminescence performance of two-dimensional NdOCl nanosheets:Under the excitation of 532nm laser,the linear spectrum of Nd³⁺appears at595nm,668nm,815nm and 910nm.This work systematically investigates the effects of thickness,temperature,laser power,stress and electric field on the photoluminescence properties of NdOCl nanosheets.It is found that the external stress could modulate the band gap of NdOCl nanosheets to enhance the PL performance;Electric field modulation is able to change the local crystal field of Nd³⁺,further improving the luminous intensity.(2)Preparation of large-area two-dimensional NdOCl film by vapor deposition:Using the confined space method,the precursor mass transfer and surface reaction are balanced,and millimeter-level(?5 mm)two-dimensional NdOCl film is realized on the sapphire substrate.Scanning electron microscopy and atomic force microscopy indicated that the thickness of the film was about forty to two hundred nanometers.Atomic force microscope characterization results show that the film is spliced by multi-point spiral growth.It is proved that NdOCl can be prepared by vapor deposition to produce high-quality films of millimeter level,which has the potential for large-scale preparation and application.