Research On CsPbBr₃ Quantum Dots Photoelectric Response Devices Based On ZnO Nanorods Arrays

Organic-inorganic hybrid perovskite materials have great potential application in various photoelectric devices such as solar cells,light emitting diodes and photoelectric response devices due to their advantages of high absorption coefficient,long charge diffusion length and high carrier mobility.However,organic-inorganic hybrid perovskites will exhibit instability of material properties under the conditions of moisture,heat or ultraviolet radiation,mainly due to volatilization of organic components in the materials and large iodide radius,which is the main obstacle for their future application.In comparison,the stability of all inorganic cesium lead halide perovskites?CsPbX₃,X=Cl,Br,I?have been improved and attracted extensive attention,among which CsPbBr₃ has better stability than that of CsPbI₃ and CsPbCl₃.In this thesis,the light absorption layer,electron transport layer and hole transport layer of the photoelectric response devices are optimized respectively,and finally the P-I-N structure photoelectric response devices based on inorganic perovskite CsPbBr₃quantum dot are fabricated.The main contents of this work are as follows:?1?Two synthetic methods of ZnO Nanorods are compared.ZnO seed layers were prepared by solvent spin coating method and magnetron sputtering method,respectively.Based on the ZnO seed layers obtained under these two different preparation conditions,the growth of ZnO Nanorods was carried out.Their crystal structure,optical properties and morphology were analyzed in detail.It was found that the ZnO seed layer obtained by magnetron sputtering was more conducive to the growth of ZnO Nanorods and their surface was much denser.?2?Ligand modification of CsPbBr₃ quantum dots?QDs?.CsPbBr₃ QDs with oleic acid?OA?and 2-hexyldecanoic acid?DA?as ligands were prepared by thermal injection method.The effect of carbon chain length of ligands on the properties of quantum dots was studied.Since 2-hexyldecanoic acid has two short carbon chains,it is easier to combine with the surface of quantum dots,and the ligand is not easy to lose,which can effectively alleviate the agglomeration problem of quantum dots.Meanwhile,the shortening of the carbon chain length of the ligand is more conducive to the recombination of electrons and holes.Therefore,the fluorescence intensity and fluorescence lifetime of CsPbBr₃ quantum dots modified by DA ligand have been significantly improved,which lays a foundation for the research of CsPbBr₃ quantum dot-based photoelectric response devices.?3?The research on CsPbBr₃ quantum dot photoelectric response devices using ZnO thin film and ZnO Nanorods as electron transport layers has been carried out.In our design,we use spiro-OMeTAD as the hole material,perovskite CsPbBr₃ quantum dots as the light absorption layer,ZnO Nanorods array as the electron transport layer to form a P-I-N structure photoelectric response device,namely ITO/ZnO Nanorods/CsPbBr₃ QDs/spiro-OMeTAD/Ag device,and perform a series of characterization tests and pre-analysis on the prepared device.It is found that when ZnO Nanorods is used as the electron transport layer,the rise time of the device is about 0.012s,the fall time is about 0.038s,and the on/off ratio is more than 3000.However,the rise and fall times of photoelectric response devices based on ZnO thin films as electron transport layers are0.8s and 1.123s respectively.The comparison shows that the performance of the photoelectric response device using ZnO Nanorods can greatly shorten the rise and decay time by 66 times and 29 times,and the switch ratio can be increased by 3000times.To sum up,this thesis is based on the research of P-I-N junction structure photoelectric response device of inorganic perovskite CsPbBr₃ quantum dots with ZnO Nanorods array as electron transport layer.ZnO Nanorods array has the advantage of directional movement of electrons,which can accelerate the movement of electrons more effectively,providing a new design idea for photoelectric response devices.