Preparation And Photoelectrical Properties Study Of The Hybrid Material Of CH₃NH₃PbI₃ Perovskite Nanoarrays And CdSe Nanobelts

At present,organic-inorganic hybrid methylamine iodide lead perovskite?CH₃NH₃PbI₃?has become a photoelectric material with excellent performance due to the direct band gap?¹.5 eV?matching the solar spectrum.However,the photodetectors based on the perovskite planarization structure often have large electrical hysteresis,slow optical response and low sensitivity,which limit its development.A particularly effective way to improve the performance of perovskite devices is to combine the perovskite layer with other functional materials.Cadmium selenide nanobelts?CdSe?have been used in the field of photodetectors because of their own excellent optical properties,but due to high resistivity and other reasons have restricted wider development.In this thesis,the construction of methylamine iodide lead perovskite nanoarrays and cadmium selenide nanobelts hybridization?CH₃NH₃PbI₃ NAs/CdSe NBs?can promote the effective separation of electron-hole pairs and greatly improve the photoelectric performance of the device.This thesis is guided by the construction of high-performance CH₃NH₃PbI₃NAs/CdSe NBs devices,and carries out a systematic study from the preparation of materials to the device performance testing.CH₃NH₃PbI₃ NAs were prepared by one-step method and two-step method,CdSe NBs were prepared by thermal evaporation and CH₃NH₃PbI₃ NAs/CdSe NBs hybrid materials were prepared by droplet method.Then through the optical microscope?OC?,scanning electron microscope?SEM?,X-ray energy analysis?EDX?,X-ray diffractometer?XRD?and X-ray photoelectron spectroscopy?XPS?to characterize its morphology,composition and structure.At the same time,Raman and photoluminescence spectroscopy?PL?were used to test and analyze its optical performance.The research results of this paper are as follows:1?Preparation of methylamine iodide lead perovskite nanowires?CH₃NH₃PbI₃NWs?by one-step method and two-step method.The morphology of the two was characterized by OC and SEM.It is found that the one-step preparation of CH₃NH₃PbI₃ NWs is ordered and arrayed;the two-step preparation of CH₃NH₃PbI₃NWs is disordered.In addition,we used EDX and XRD to characterize the structure and composition of the two.The results show that the CH₃NH₃PbI₃ NWs prepared by the two methods have good crystallinity.XPS was also used to characterize the one-step preparation of CH₃NH₃PbI₃ NWs,and it is found that the purity of CH₃NH₃PbI₃ NWs is very high.In addition,we tested the PL of CH₃NH₃PbI₃ NWs,and the results show that CH₃NH₃PbI₃ NWs have fewer defects and good crystallinity.2?Preparation of CdSe NBs by thermal evaporation.The morphology was characterized by SEM.The results show that the surface of CdSe NBs is smooth.In addition,using EDX,XRD,XPS to characterize its structure and composition,the results show that CdSe NBs have good crystallinity.In addition,we tested Raman and PL of CdSe NBs,and the results show that CdSe NBs have fewer defects and good crystallinity.3?The droplet method was used to hybridize the CH₃NH₃PbI₃ NAs prepared by the one-step method and the CdSe NBs prepared by thermal evaporation.The morphology of CH₃NH₃PbI₃ NAs/CdSe NBs was characterized by OC and SEM.It is found that CH₃NH₃PbI₃ NAs and CdSe NBs are successfully combined.In addition,we tested the PL of CH₃NH₃PbI₃ NAs/CdSe NBs.And the results show that the change in the PL peak is caused by the effective separation of the electron-hole of CH₃NH₃PbI₃ NAs/CdSe NBs.4?The CH₃NH₃PbI₃ NAs/CdSe NBs device was prepared and compared with a single device.It is found that the photocurrent of the CH₃NH₃PbI₃ NAs/CdSe NBs photodetector is 5600%higher than that of the pure CH₃NH₃PbI₃ NAs photodetector,the dark current is increased by 3600%and the photo-dark current ratio is increased by 157%under the power density of 21.57 mW/cm² and the bias voltage of 1 V;the photocurrent is increased by 1670%compared to the pure CdSe NBs photodetector,and the photo-dark current ratio is increased by 300%.The responsivity,quantum efficiency and dectiectivity of CH₃NH₃PbI₃ NAs/CdSe NBs photodetector at 480 nm is 1160%greater than that of pure CH₃NH₃PbI₃ NAs.The responsivity,quantum efficiency and dectiectivity of CH₃NH₃PbI₃ NAs/CdSe NBs photodetector at 780 nm is 720%greater than that of pure CdSe NBs.The reaction time of CH₃NH₃PbI₃NAs/CdSe NBs is also reduced to 0.95 ms/1.3 ms.The results show that the hybrid structure of CH₃NH₃PbI₃ NAs/CdSe NBs promotes the effective separation of electron-hole pairs and greatly improves the photoelectric performance of CH₃NH₃PbI₃ NAs/CdSe NBs devices.The research results of this paper are expected to be used to construct high-performance photodetectors and other photoelectric devices,which will provide more possibilities for the development of future wavelength-controlled photodetectors.