Study On The Influernce Of Doping And Interfacial Modification Of Perovskite Light Absorbing Layer On The Perovskite Solar Cells

Because of the characteristics of low cost,high absorption coefficient and low band gap for the perovskite materials,its photoelectric conversion efficiency has exceeded 23%in only ten years since the invention of the perovskite solar cell?PSC?in 2009.The increase in efficiency of perovskite solar cells is encouraging,but battery structure and device stability issues have not been properly addressed.In this paper,the effects of doping and interfacial modification on the performances of PSC were studied.The main point is using dopant to improve the quality of the perovskite photoactive layer and interface modification to improve the interface charge transport as well as modifying the hydrophilic interface to promote the stability of the device.The related work has the following contents:?1?The PEDOT:PSS was directly introduced as an additive into the CH₃NH₃PbI_3-xCl_x perovskite absorber layer.After optimizing the PEDOT:PSS dopant ratio,we obtained a high quality film having large crystal grains improving the photoelectric performance of the perovskite layer.As the studies shown,the defects into PEDOT:PSS doped perovskite layer are effectively passivated due to the complexation effect between PEDOT:PSS and CH₃NH₃PbI_3-xCl_x,resulting in longer carrier lifetime.The PSC with the 1.5 v%PEDOT:PSS dopant finally achieved a PCE of 17.56%.?2?The PSC with the architecture of Glass/ITO/PEDOT:PSS/MoS₂/CH₃NH₃PbI₃/PCBM/Bphen/Ag was prepared by using the MoS₂ as a buffer layer between the PEDOT:PSS and CH₃NH₃PbI₃ layers.We obtained the PCE of 16.32%and the good device stability?65%of the initial efficiency after being stored in air for 20 days?.Studies have shown that due to the energy level matching between the MoS₂ buffer layer and CH₃NH₃PbI₃,the charge extracting and transporting properties of the HTL layer are improved.In addition,the MoS₂ buffer layer can also prevent the direct contact of the PEDOT:PSS layer and the CH₃NH₃PbI₃ layer,reducing the influence of moisture absorbed by the hydrophilic PEDOT:PSS film on the perovskite film to improve the humidity stability and thermal stability of the perovskite solar cell.?3?The device performance and stability of the perovskite solar cell are effectively improved by using MoS₂ as an additive of the CH₃NH₃PbI₃ perovskite layer.The results show that MoS₂ as an additive can form a CH₃NH₃PbI₃:MoS₂ bulk heterojunction structure with the perovskite resulting into the increase of the perovskite grain size.In addition,the larger CH₃NH₃PbI₃:MoS₂ film grains can effectively reduce the number of grain boundaries in the perovskite film,preventing the water absorbed by the hydrophilic PEDOT:PSS film from immersing into the perovskite film,thereby slowing the decomposition of the perovskite film.After experimental optimization,the perovskite solar cell device based on CH₃NH₃PbI₃:MoS₂?10 v%?perovskite film can obtain the PCE of 18.31%and the good stability that maintaining the 87%of the initial efficiency after being placed in air for 20 days.