| The photodetector is an electronic device that converts optical signals into electrical signals,and is widely used in optical communication,imaging,medicine,and military fields.In recent years,inorganic perovskite materials have been considered as promising photodetection materials by scholars due to their merits of high carrier mobility,high absorption coefficient,and long carrier diffusion distance.In this paper,the interface properties of CsPbBr3 are mainly controlled by atomic layer deposition technology.In-depth research was conducted on the problems of low responsivity,high dark current and instability of inorganic perovskite CsPbBr3-based photodetectors,and the following main conclusions were obtained:1.The modification of ALD interface layer regulates the morphology,structure and performance of CsPbBr3 thin films.?1?Morphology and structure control:Based on atomic layer deposition?ALD?technology,a 1.5 nm ultra-thin Al2O3 interface layer is introduced between the FTO/CsPbBr3 thin film,which helps to improve the compactness of the CsPbBr3 perovskite thin film,and also promotes CsPbBr3 film grows preferentially along the?200?crystal direction.Compared with the unmodified detector,dark current can be suppressed by 3 orders of magnitude;?2?Photoelectric response characteristic regulation:To improve device responsivity and response speed,10 nm thick Ti O2 film is introduced through ALD technology between CsPbBr3/Au.On the one hand,Ti O2 is used as an electron transport layer to improve carrier separation efficiency.On the other hand,the Ti O2 interface layer can modify the CsPbBr3interface defect state,and the photocurrent of the photodetector is increased by 2 orders of magnitude.In addition,ALD-Ti O2 protects the photodetector and improves the stability of the detector.The optimized CsPbBr3 perovskite detector?Al2O3/CsPbBr3/Ti O2 photodetector,ACT photodetector?exhibits ultra-low dark current(10-11 A),high detectivity(1.88×1013 Jones)and wide linear dynamic range?172.7 d B?,the photocurrent remained 96%after the photodetector was exposed to air for 100 days.After the flexible ACT photodetector is bent 3000 times under the condition of 90°bending,the switching ratio can maintain 76.8%of the original value.2.Effect of ALD-NiOx modification layer on the photodetection performance of CsPbBr3perovskite detectors.A layer of NiOx is pre-deposited on the FTO as an electron blocking layer to suppress the dark current of the photodetector.The optimized photodetector?NiOx/CsPbBr3/Ti O2 photodetector,NCT photodetector?exhibits ultra-low dark current(10-11 A),the linear dynamic range is as wide as 186.7 d B and the minimum detectable light intensity is as low as 857 p W/cm2.The NCT detector can still show obvious photoresponsivity under the weak signal.Further,the NCT photodetector is assembled in a laser focused transmission imaging system,and the imaging resolution is better than 25?m,which realizes a clear imaging of the two-dimensional code under the weak light of 4 n W/cm2.3.Developed an ALD-assisted chemical vapor anion exchange method to regulate the CsPbBr3 energy band structure and used to regulate the active layer of inorganic perovskite photodetectors.CsPbBr3 perovskite undergoes an anion replacement reaction with Cl-ions in Ti Cl4 in the reaction chamber of the ALD system.As the Br-ions in the CsPbBr3 film are gradually replaced by Cl-ions,CsPbBr3 is converted to Cs Pb Cl3,the band gap increases,the absorption edge of the perovskite film can be blue-shifted from 518 nm to 410 nm.Further,based on the interface passivation process of work 1 and work 2,the response regulation of the inorganic perovskite photodetector from the near ultraviolet to the visible band is realized... |
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