Chemical Bath Deposition Of Carrier Transport Layer To Improve Performance Of Perovskite Solar Cells

Perovskite solar cells have become a booming photovoltaic technology due to their simple preparation process,low cost and higher power conversion efficiency.In addition to the perovskite absorption layer,the carrier transport layer is also an important part of the perovskite solar cell,which material and microstructure are important to determining their efficiency and stability.The tin oxide(SnO₂)with wide band gap and higher electron mobility has emerged as an attractive alternative ETL.Planar tin dioxide is the most commonly used inorganic electron transport layer,but there are few reports of its mesoporous devices structure because of the degradation of hole-blocking property after high temperature sintering.Therefore,the fabrication of mesoporous SnO₂ layers with high mechanical strength and excellent electron-transporting/hole-blocking behavior is still a challenge,and it will be of great significance to achieve a breakthrough in device stability.Here,the chemical bath deposition method was optimized to realize low-temperature in-situ deposition of mesoporous SnO₂ layer on FTO substrates.On one hand,the increased interface contact area improves electron injection from the perovskite layer to the SnO₂,yielding an impressive increase of the power conversion efficiency from 22.09%to 24.11%.And on the other hand,thanks to the increased mechanical strength of the interface,the device with mesoporous SnO₂ retains 90%of its initial power conversion efficiency after 1000 h operation under continuous one-sun illumination.In addition to electron transport layer,hole transport layer is also an important part of perovskite solar cells.Nickel oxide(Ni O_x)has become the most widely used hole transport layer material due to its high hole mobility,suitable energy level matching and chemical stability.However,the tendency of Ni O_x to aggregate during film formation leads to poor morphology and low reproducibility.Despite important advances in the application of Ni O_xfor PSCs,a thorough understanding of material control over aggregation is lacking.(2)Here,we have achieved uniform and dense nickel oxide films by using a method of slowly releasing the nickel ions from the[Ni(H₂O)_6-x(NH₃)]²⁺complex.The formed[Ni(H₂O)_6-x(NH₃)]²⁺by the ammonium chloride(NH₄Cl)enabled Ni ions to undergo an intermediate-state transition reaction during the chemical bath deposition method for the homogeneous nucleation of Ni O_xparticles.Ni O_x films deposited using the NH₄Cl-based precursor realizated a uniform morphology compared to those of control devices.Devices with NH₄Cl-based Ni O_x exhibited enhanced reproducibility and achieved a PCE of 19.00%with a J_SC of 23.53 m A·cm^-2,V_OC of1.052 V,and a fill factor of 76.74%.