Research Of High Performance Perovskite Solar Cells Based On Metal Oxides Hole Transporting Layer

In recent years,organic and inorganic hybrid perovskite solar cells（PSCs）have attracted worldwide attention.Not only because of the rapid development of perovskite solar cell conversion efficiency,but also because of the low cost,simple preparation technology,large area preparation.Therefore,it is necessary to study the high-efficieny and low-cost preparation process for perovskite solar cells.The thesis is divided into two parts.It is first part that the inverted-plane perovskite solar cells were fabricated by incorporating nanoparticle MoO_x into the CH₃NH₃Pb I_3-xCl_x perovskite active layers.The results showed that the device performances had been significantly improved,mainly reflected the enhancement of the open-circuit voltage.The testing of the Mo distribution found that Mo element was mostly distributed on grain boundaries by using energy dispersive spectrometer.In addition,the conductive atomic force microscopy spectroscopy verified that the surface current of the perovskite-MoO_x is larger than that of the pure perovskite film.The relationship between capacitance and frequency was tested and indirectly proved that bulk heterojunctions can rapidly separate the carriers.The ultrafast transient absorption spectroscopy measurements provided a reasonable explanation for the MoO_x-induced rapidly separating of the carriers.Our research illustrates the application potential of bulk heterojunctions in the perovskite solar cells through doping the MoO_x inorganic materials into the perovskite active layer,as well as further consolidates the role of bulk heterojunctions in perovskite active layer.The bulk heterojunction formed in the perovskite active layer promotes the extraction and separation of carriers,reduces the recombination of electrons and holes,increases the open circuit voltage of the device,and improves the conversion efficiency of the device.It is second part that Ni O_x is a wide band gap p-type oxide semiconductor.It was prepared and studied as a hole transport layer.It also has good optical transparency,chemical stability and the capability of aligning the band edges.Ultra-thin Ni O_x films with much less absorption loss were prepared by evaporation deposition with heat treatment with highly precise control over thickness without any pin holes.Although improvement traditional device performance has been made by external controls including electrical doping and interfacial engineering,there has been a lack of research on the fundamental material design.Thus,a greatly improved performance of Ni O_x as a hole transport layer in the perovskite solar cells through the control of not only heat treatment but also surface hydroxyl groups is expected.We have observed an apparent reduction of the work function in Ni O_x when the heat treatment temperature is rise,which attributes to the chemical composition and surface structure of Ni O_x changes,and which leads to the hole extraction performance and resistivity of Ni O_x changes.Therefore,heat treatment successful control Ni O,Ni OOH and Ni₂O₃ generated in Ni O_x layer.In a word,it is proved that Ni O_x films prepared by hot annealing process have high transmittance,stable chemical properties and adjustable band gap.The perovskite solar cells conversion efficiency increase based on Ni O_xthrough maximizing the composition rate and matched work function.