Application Of Cu-Based Inorganic Hole Transport Materials In Carbon Counter Electrode Perovskite Cells

Perovskite cells are typical representative of the third generation of solar cells,whose photoelectric conversion efficiency has increased from the initial 3.8%to 25.7%certified,and are hailed as the"new hope in the photovoltaic field".However,perovskite cells also have some obvious disadvantages:perovskite materials are unstable in water and oxygen,the preparation process of organic hole transport materials is complex and unstable,and the metal electrode materials are expensive.These disadvantages greatly limit the industrial development of perovskite solar cells in the future.Therefore,it is of great significance to explore inorganic hole transport materials and non-metallic electrode materials with low cost,simple process and high stability.The specific work of this paper is as follows:（1）In order to solve the problem of low production of Cu₂Zn Sn S₄synthesized by hot injection method（less than 1 g）.In this paper,Cu₂Zn Sn S₄nanocrystals were synthesized by one-pot method.After optimizing the synthesis parameters,a large amount of Cu₂Zn Sn S₄nanocrystals（6.5 g）were successfully obtained.Cu₂Zn Sn S₄nanocrystals were treated by ligand exchange process and used as hole transport materials for perovskite solar cells.Carbon electrode was prepared by blade coating method instead of expensive metal electrode.The structure of the Prepared perovskite solar cell is FTO/Sn O₂/MAPb I₃/Cu₂Zn Sn S₄/Carbon.The cell achieved a photoelectric conversion efficiency of 16.1%and showed almost no degradation after nearly 30 days of stability testing.（2）In order to further improve the performance and long-term stability of perovskite cells,Cu₂Zn Ge S₄with a wide band gap were selected as the hole transport layer of the cells.In this work,Cu₂Zn Ge S₄were synthesized by one pot method,preparation of structure for FTO/Sn O₂/FAPb I₃/Cu₂Zn Ge S₄/Carbon perovskite solar cells.The average open circuit voltage of the cell is as high as 1.075 V,The average photoelectric conversion efficiency of the cell is 17.50%,and the highest efficiency is 18.00%.We performed performance tests on the device for up to 60 days,and the cell showed excellent long-term stability.（3）From the perspective of adjusting the band gap structure of semiconductor materials,the positions of valence band and conduction band of Cu₂Zn Ge_xSn_1-xS₄compound can be optimized by changing the Ge/Sn ratio,so as to better match the energy level of perovskite material,thus improving the efficiency of the cell.In this work,Cu₂Zn Ge_xSn_1-xS₄nanocrystals were synthesized by one-pot method,where x=0.0,0.5,1.0.Then the nanocrystals were treated by ligand exchange process,preparation of the perovskite solar cells structure for FTO/Sn O₂/FAPb I₃/Cu₂Zn Ge_xSn_1-xS₄/Carbon.When Cu₂Zn Ge_0.5Sn_0.5S₄nanocrystalline is used as the hole transport layer of perovskite cell,the open-circuit voltage of the device is up to 1.13 V,and the photoelectric conversion efficiency of the cell reaches 19.75%.