Investitagation On Photoelectric Characteristics And Photodetection Application Of Inorganic Semiconductor Quantum Dots Heterogeneous Multilayer Structure

Compared with traditional epitaxial growth and lattice matched bulk semiconductor optoelectronic materials,solution synthesized inorganic quantum dots have the advantages of low cost,high flexibility and easy integration,as well as excellent light absorption and size related optoelectronic properties,which make them widely used in various optoelectronic devices,but their optoelectronic properties are usually lower than those of traditional materials,which still limits their further development.With the further research,people pay more attention to the quantum dot heterojunction interface,which can promote charge separation by manipulating band bending and built-in electric field,so as to enhance its photoelectric performance.Therefore,choosing appropriate quantum dots to form heterostructures is very important to improve their photoelectric properties.Common semiconductors such as cesium lead iodine quantum dots,lead sulfide quantum dots and zinc oxide nanocrystals can form heterojunctions conducive to charge separation.Therefore,in this thesis,we designed several quantum dot heterostructures to enhance their photoelectric properties and optical detection performance through charge separation at the interface and synergy between layers.Our research provides a new idea for the application of multilayer heterostructures based on inorganic semiconductor quantum dots in high-performance optoelectronic devices.The research of this paper is summarized as follows:1.A heterobilayer structure composed of cesium lead iodine quantum dots（CsPbI₃ QDs）,lead sulfide quantum dots（PbS QDs）and zinc oxide nanocrystals（ZnO NCs）was prepared by thermal injection combined with spin coating technology.The heterojunction interface of this layered structure can realize the efficient separation of photogenerated carriers.Combining the long carrier lifetime and wide spectral absorption of PbS QDs with the high carrier mobility and high optical absorption coefficient of CsPbI₃ QDs and ZnO NCs,the heterobilayer structure has significantly enhanced the optical detection performance.2.CsPbI₃/PbS/ZnO heterogeneous three-layer nanostructures were prepared by simple liquid-phase thin film spin coating technology.The efficient separation of photogenerated carriers at the heterojunction interface greatly improves the optical detection performance of CsPbI₃/PbS/ZnO structure.Under 405 nm light excitation,compared with single component ZnO,PbS or CsPbI₃ photodetector,CsPbI₃/PbS/ZnO heterostructure photodetector have more than 100 times enhancement in optical responsivity,optical detection rate and external quantum efficiency.3.Gold cuprous oxide nanoparticles（Au@Cu₂O）were synthesized by wet chemical method。CsPbI₃/Au@Cu₂O metal semiconductor hybrid heterostructure and PbS/Au@Cu₂O/PbS sandwich structure.These two structures combine the metal surface plasmon effect and the efficient separation of photogenerated carriers at the heterojunction interface,which greatly improves its optical detection performance.Under the excitation of 532 nm light,the two structured light detectors are compared with a single one Au@Cu₂O or PbS photodetector,its optical response,detection rate and external quantum efficiency have been significantly enhanced.These heterostructures combine the processing technology of low-cost and easy solution treatment with the characteristics of long carrier life and high optical absorption coefficient.Through the synergy between the layers and the efficient charge separation at its internal heterostructure interface,the photoelectric performance of heterostructures is significantly improved.Therefore,this kind of quantum dot based heterogeneous multilayer nanostructure has broad application prospects in the field of optoelectronics.