Study On The Fabrication And Performance Of Perovskite Semiconductor Based Photoelectronic Devices

Optoelectronic devices are various functional devices that are fabricated with semiconductor photon-electron（or electron-photon）conversion effects.It has found essential value and application prospects in many areas,including in-household cameras,military night vision,missile warning,medical detection,face recognition,sky-warning.Perovskite,as a star material in recent years,has a series of excellent properties,such as high absorption coefficient,tunable bandgap,high carrier mobility,low preparation cost,and so on.These features render perovskite one of the promising material,which may replace the traditional semiconductor material Si for constructing high-performance optoelectronic devices.Therefore,it is of great significance to study various kinds of optoelectronic devices based on perovskites to promote their development and applications.In this thesis,we have sensitively studied different kinds of optoelectronic devices based on perovskite materials,inculding high-performance perovskite/Pt Se₂heterojunction photodetector,perovskite photocoupler,perovskite deep ultraviolet image sensors,and perovskite/Si heterojunction integrated photodetectors array.The main results are summarized as follows:1.We constructed a self-driven heterojunction photodetector composed of Cs-doped FAPbI₃ and multilayer Pt Se₂.The large area two-dimensional Pt Se₂ nanofilm was first synthesized through a thermal-assisted selenization method.Then,the perovskite was deposited on the surface of the Pt Se₂ by the one-step spin-coating method to construct the photodetector with broadband photoresponse from the ultraviolet to the near-infrared wavelength region.Further photoresponse analysis revealed that the heterojunction device showed outstanding photosensitive characteristics with a large I_light/I_dark ratio of5.7×10³,a high responsivity of 117.7 m A W^-1,and a specific detectivity of 2.91×10¹²Jones at zero bias.More importantly,the device had a fast response speed with the rise/fall times of about 78/60 ns.In addition,it was also observed that the Pt Se₂/perovskite photodetector could almost retain its photoresponse properties after storage in ambient conditions for three weeks,suggesting an excellent air stability.2.By integrating a perovskite photodetector and a perovskite quantum dot light-emitting diode（LED）on a glass substrate,a full perovskite-based photocoupler has been realized.In such a device,the perovskite quantum dot LED served as the input and the perovskite photodetector acted at the output.Consequently,a high current transmission ratio of 3.35%was successfully achieved.The device had a breakneck response speed of8/8.26μs for rise/fall time.Furthermore,the photocoupler was connected to a typical base amplifier circuit,which could achieve a current amplification of 50 times,up to 172.6%.The high value was comparable to commercial photocouplers.3.We successfully prepared all inorganic,lead-free Cs₃Cu₂I₅ single crystal particles thin film,based on which a high-performance UV photodetector was fabricated.According to the photoresponse characterization,the perovskite device exhibited nearly no sensitivity to visible illumination with the wavelength of 405 nm but exhibited pronounced sensitivity to both DUV and UV light illumination with a fast response speed of 26.2/49.9 ms for rise/fall time.The I_light/I_dark ratio could reach 127.What is more,the responsivity and detectivity were calculated to be 64.9 m AW^-1 and 6.9×10¹¹ Jones,respectively.In addition,the device could keep its photoresponsivity after storage in air environment for a month,revealing a outstanding ambient stability.It was also found that the capability of the Cs₃Cu₂I₅ crystalline film device could readily record still DUV images with acceptable resolution.4.We constructed an integrated photodetectors array comprising 8×8 device units based on MAPbI₃/Si heterojunctions.Under 970 nm light illumination,the heterojunction photodetector exhibited a responsivity of 3.02 m AW^-1,a specific detectivity of 2.99×10¹¹Jones,and I_light/I_darkratio of 3.41×10³,respectively.Further electrical analysis revealed that the as-fabricated photodetector arrays exhibited outstanding uniformity and repeatability,endowing it with outstanding imaging sensing capability.