PbS Uantum Dots Capped With ZnS For Application In Perovskite Solar Cells

Semiconductor quantum dots have special properties such as quantum size effect,multi-exciton effect,and so on,exhibiting characteristics different from those of macro-block materials.Therefore,it is widely used in optoelectronic devices,life medicine and other fields.Traditional colloidal quantum dot materials use organic molecules as the coating material,and the passivation effect on the surface state is at the molecular level,and the stability is poor.In this paper,PbS QDs capped with ZnS were prepared by spin-coating-assisted successive ionic layer adsorption and reaction（SILAR）.The all-inorganic quantum dot system reduces the passivation effect of the surface state from the molecular scale to the atomic scale,and improves the stability of the quantum dot and its solar cell device.Through the structure control of QDs,high-quality PbS QD films were obtained.The main content of this thesis consists of two parts,the regulation of ZnS-coated PbS QDs structure and its application as a hole transport layer in perovskite solar devices.The details are as follows:（1）The spin-coating times and the total number of cycles of ZnS and PbS during the preparation of PbS QDs by spin-assisted SILAR were studied.The optical properties,surface morphology effects and crystallographic properties of the films were studied.The results show that ZnS（6）/PbS（2）can be used as spin coating parameters in one cycle,and quantum dots with uniform size and uniform distribution can be prepared.At the same time,the influence of quantum dot growth conditions（precursor solution,spin coating environment）on the growth of quantum dots was also investigated.（2）The above-prepared PbS quantum dot film was used as a hole transport layer,and its effect was studied through various performance parameters of the perovskite solar device.After optimization of structure control,The device has a maximum photoelectric conversion efficiency（PCE）of 9.1%,a corresponding open circuit voltage(V_oc)of 0.82V,a short circuit current density(J_sc)of 14.9 mA/cm²,and a fill factor（FF）of 74.2%.PCE increased by 40%compared to a standard device without a hole transport layer.