| Among numerous photovoltaic devices,organic-inorganic hybrid perovskite solar cells(PSCs)have recently reached certified efficiencies up to 22.7%in a few years,which exceed the efficiency of organic solar cells,dye-sensitized solar cells,and polysilicon cells.More importantly,perovskite materials possess high charge carrier mobility,large absorption coefficient,small exciton binding energy,and long exciton diffusion length.Meantime,perovskite materials have advantages of low cost,high absorbance and solution processing.The above merits all indicate that PSCs have a great prospect of commercial application.At present,PSCs are considered as the most promising photovoltaic technology in the current generation of solar cells.However,the stability of PSCs is still unsatisfactory,which is the main bottleneck hindering commercialization of PSCs;To further improve efficiency and mitigate hysteresis in J-V test is also a challenging issue.The research content of this thesis focuses on the interfacial engineering and modification for high-performance PSCs.The performance of PSCs was improved through rational design and introduction of organic or inorganic interfacial layers.Chapter 1.First,the structure of perovskite materials,and their composition,preparation process,working principle and development history of PSCs are introduced.Then,the hysteresis phenomenon and stability of PSCs are summarized,and their corresponding solutions are discussed.Chapter 2.A novel and simple scenario that depositing both amino acid and acid at the TiO2/perovskite interface leads to obvious improvement in both the performance of PSCs.Amino groups on aminocaproic acid promoted electron transfer from perovskite layer to TiO2 layer,and alkyl chains from caproic acid resisted moisture.These two organic molecules worked cooperatively to promote the efficiency of modified cells to 18.21%.Chapter 3.Interface engineering of the TiO2/perovskite interface has resulted in improved cell performance,but the deficient electron transport mobility of TiO2 as electron transport layer(ETL)has inhibited further improvement in PSCs’performance.To avoid this problem,we chose ZnO,which has superior electron transport properties,as an ETL.Yet the Lewis basic nature of ZnO surface leads to deprotonation of the perovskite layer,resulting in serious degradation of PSCs.Here,we devised a novel strategy to convert ZnO surface into ZnS by thiourea-treatment,and then used the ZnO-ZnS hybrid nanostructure as Efficient ETL.The sulfur on ZnO-ZnS surface bound strongly with lead(Pb2+)ions from the edge of perovskite layer and generated a unique pathway of electron transport to reduce interfacial charge recombination and accelerate electron transfer at the ZnO/perovskite interface,yielding a champion efficiency of 20.17%.Due to the stability of ZnS nature,the stability of PSCs has a great improvement.Chapter 4.Final chapter summarizes the research content of this paper,predicts the development trend of PSCs at the base of reported foundation,and provides future research suggestions. |
