Preparation And Photoelectric Response Characteristics Of Organic-inorganic Hybrid Perovskite Self-powered Photodetector

Photodetector is a kind of device that can convert optical signal into electrical signal,and it is the core component of modern photoelectric system.It has been widely used in various fields of people’s production and life,such as imaging,communication,environmental monitoring,early warning and medicine.With the development of science and technology,people have put forward higher requirements for photoelectric system.As the core component of photodetector,it is developing towards the direction of high responsivity,low energy consumption,fast response speed,miniaturization and multi-function.At present,the traditional inorganic semiconductor photodetectors represented by Si,Ga N and In Ga As still dominate the market.However,the preparation process of this kind of material is complex and expensive,which limits its wide application.In recent years,organic-inorganic hybrid halide perovskite CH₃NH₃Pb X₃（MAPb X₃）semiconductor materials have been widely used in the field of photodetector and X-ray detector because of their advantages such as large absorption coefficient,high carrier diffusion length,adjustable optical band gap,excellent photoelectric characteristics and flexible and simple preparation process.However,implementing multifunctional,high-performance optoelectronic devices remains challenging due to the limitations of device structure.In view of this,it is of great significance to utilize the excellent photoelectric properties of perovskite semiconductor materials and design reasonable device structure to realize multifunctional self-powered photodetector.In this paper,a series of multifunctional and high-performance self-powered photodetectors are designed and prepared based on the structure-function relationship between the excellent photoelectric properties of organic and inorganic hybrid halogen perovskite materials and the device structure,and their performance and working mechanism are studied as follows:（1）Firstly,a simple solution process is developed to rapidly prepare a series of gram-scale MAPb X₃ microcrystalline materials.Based on this material,a series of planar photodetectors with asymmetric Schottky contacts are designed and prepared.Based on the charge collection narrowing mechanism and by adjusting halogen polar groups,a series of self-powered photodetectors with both narrow band and broad band detection functions are realized,and the working performance of the series of photodetectors is systematically studied.These detectors not only exhibit excellent photodetection capability,but also excellent X-ray detection capability.Taking CH₃NH₃Pb I₃（MAPb I₃）device as an example,after 200 hours in the air in unpackaged condition,its spectral response performance still remains at 98.14%of the initial response,showing good air stability.In addition,it has a sensitivity of 3560μC Gy_air^-1 cm^-2 for X-ray detection in self-powered mode.In addition,the self-powered photodetector is successfully integrated into optical communication systems as a signal receiver to transmit text and recover transmission signals with high fidelity.Therefore,the device has remarkable anti-interference ability and can achieve the effect of secure optical communication.（2）In order to solve the problem that there are a large number of grain boundaries in the perovskite microcrystalline film,which hinders carrier transmission and seriously affects the performance of photodetectors,this chapter adopts the growth of perovskite single crystals to inhibit the influence of grain boundaries on the device performance.By means of solution epitaxy growth method and space confined method,CH₃NH₃Pb Br₃（MAPb Br₃）single crystal epitaxy in the horizontal direction of CH₃NH₃Pb Cl₃（MAPb Cl₃）single crystal can be controlled to prepare perovskite single crystal heterojunction with clear interface and high crystal quality.The coating thickness of epitaxial layer can be carefully controlled by adjusting the growth time.Due to the excellent built-in electric field of the single crystal heterojunction,the heterojunction detector exhibits remarkable rectification behavior and excellent photodetection and X-ray detection performance under self-powered conditions,including high responsiveness(26.8 m A W^-1),fast response time（8/613μs）,As well as high X-ray detection sensitivity(868μC Gy_air^-1cm^-2)and low detection limit(15.5 n Gy_air s^-1).After 120 days in the air environment,the spectral response performance of the unpackaged single crystal heterojunction detector still maintains 99%of the initial response,showing excellent air stability.In addition,the device exhibits high fidelity UV imaging capability in a single pixel imaging system at zero bias voltage.（3）In order to solve the problem that the functions of traditional heterojunction devices are fixed after preparation,a series of MAPb X₃/Zn O reconfigurable self-powered photodetectors with adjustable spectral response are assembled using a simple physical stacking method.Zn O microwires and MAPb X₃ polycrystalline films in the heterojunction devices can be assembled and disassembled multiple times.It can be further assembled into heterojunction photodetectors with different spectral response characteristics.These devices show good responsivity(～1 m A W^-1)and fast response speed（～100μs）at 0 V.In addition,the actual imaging capability of Zn O/MAPb I₃ self-powered heterojunction photodetectors is investigated,which achieves high fidelity imaging under infrared light.（4）In order to overcome the problem of ion migration in three-dimensional perovskite and affect the stability of the material,two-dimensional perovskite（PEA）₂Pb I₄single crystal was grown by cooling crystallization method.A metal-semiconductor-metal（MSM）planar device structure was constructed by evaporation of asymmetric metal electrodes Pt and Ag on a single crystal surface,and a high performance self-powered photodetector was realized.By using the Schottky barrier between different metals and perovskites,the built-in electric field is effectively introduced into the device,which makes the photodetector show excellent spectral response without external power supply.These include high light responsiveness(114.07 m A W^-1),fast response speed（1.2ms/582 ms）,and high detection rate(4.56×10¹² Jones).At the same time,the self-powered photodetector has excellent environmental stability.The spectral response of the unpackaged device can still maintain 99.4%of the initial response after 84 days in the air environment.In addition,the photodetector is used as the sensor pixel in the imaging system,which has the ability of high fidelity visible light imaging under the self-powered condition.