Preparation And Modification Of TiO₂/CsPbBr₃ Perovskite Solar Cells With Mesoporous-planar Heterojunction

The power conversion efficiency（PCE）of the third generation of perovskite-based solar cells（PSCs）have continuously breakthroughs in efficiency,which has now achieved up to 24%,depending on the outstanding optoelectronic characteristics of perovskite materials.Solar cells,as the important and renewable clean energy,have undergone a long development process.The PSCs were expected to be realized commercialization by scientists.The hole-free transport layer solar cells do not require the use of expensive hole transport layers（such as Spiro-Me OTAD）and precious metal electrodes,and have the advantages of good stability,long life and low cost.Therefore,in this study,CsPbBr₃ perovskite material with excellent thermal and high chemical stability was selected to prepare a hole-free transport layer battery with Ti O₂/CsPbBr₃/carbon electrode as the basic device structure.The photovoltaic performance of the solar cell was improved by optimizing the electronic transport layer and optical absorption layer of CsPbBr₃perovskite solar cell.X-ray diffraction（XRD）,X-ray photoelectron spectroscopy（XPS）,field emission electron microscopy（FESEM）,transmission electron microscopy（HRTEM）,UV-Vis,PL and TRPL were used to analyze and characterize the materials we discuss,and J-V measurement and AC impedance（EIS）were used to characterize the photoelectric performance of solar cells.The main research is as follows:（1）The modification of Ti O₂electron transport layer of CsPbBr₃perovskite solar cell was studied.We modify the interface between Ti O₂/CsPbBr₃with Pb S colloidal quantum dots（CQDs）by the interface engineering technology,and constructed the PSCs with hybrid structure of mesoporous planar heterojunction.Different amounts of CQDs was spin-coated on mesoporous Ti O₂（m-Ti O₂）to obtain Ti O₂/Pb S photoanodes with different morphologies.The quality of CsPbBr₃ perovskite film can be improved by using the appropriate amount of Pb S CQDs modified the Ti O₂/CsPbBr₃ interface.The photovoltaic properties of different perovskite solar cells were characterized.The results showed that an increased PCE up to 5.04%is achieved for solar cells deposited on m-Ti O₂ for one cycle（Pb S-1）,which was about 2 times of 2.45%for pristine CsPbBr₃perovskite（Pb S-0）.（2）The modification of CsPbBr₃ perovskite materials by element doping technology.Different concentrations of Sn Br₂ was doped in perovskite to obtain Pb-Sn binary perovskite films,and to determine the performance of perovskite films.The results show that the structure of perovskite become more stable due CsPbBr₃ perovskite solar cell modified with 0.5%Sn Br₂ is achieved up to3.23%,which shows excellent stability.（3）The further modification of Cs Pb_0.995Sn_0.005Br₃ perovskite materials.We differences of crystalline and photoelectric properties between Pb-Sn binary perovskite and Pb-Sn-TM bimetal-ion doped ternary perovskite films.The results show that the PCE of Pb-Sn-TM ternary perovskite solar cells all have improved.The PCE of Pb-Sn-Mn is 5.43%,which is 1.68 times higher than that of Pb-Sn binary perovskite solar cells（3.23%）.On the one hand,perovskite the quality of Pb-Sn binary perovskite film which can inhibit the hole electron recombination.Within 30 days,the PCE of Pb-Sn binary PSC was decreased by22.6%,while that of Pb-Sn-Mn ternary PSC was 12%,which shows the best stability.