Study On The Performance Of Perovskite Solar Cells Fabricated By Ligand Engineering

Perovskite solar cells(PSCs)originated from dye-sensitized solar cells.In 2009,metal halide(CH₃NH₃Pb I₃)was firstly applied by Professor Miyasaka to replace dyes as photosensitive catalyst to fabricate the PSCs with a photoelectric conversion efficiency(PCE)of 3.8%.During these decades of development,the PCE of PSCs has continued been refreshed(the efficiency of the latest NREL certification has reached 25.5%).In this paper,We investigated the influence of the precursor solvent,film components and interface modification on the quality of the film and device.Here is the main research content.(1)Study on performance perovskite film and solar cells fabricated based on the precursor solvent adjustment.Three solvents with different coordination abilities(N-methylpyrrolidone(NMP),dimethylsulfoxide(DMSO)and tetramethylsulfoxide(TMSO))were introduced into the perovskite precursor solution to investigate the perovskite nucleation mechanism,film quality and device performance.The results show that the perovskite film formed by NMP with weak coordination ability exhibits the small but uniform crystal grains,which can improve the open circuit voltage(V_OC)and fill factor(FF)of the device;while due to the strong coordination ability of TMSO,the TMSO-based perovskite films show larger grain size and thick film,and the corresponding devices exhibit good current density(J_SC);However,the higher defect density and carrier recombination have an adverse effect on FF based on DMSO devices.The research laid the foundation for the subsequent preparation of high-quality perovskite films.(2)Study on performance perovskite film and solar cells fabricated based on the precursor composition adjustment.The ratio of organic cations(MA and FA)in the perovskite precursor solution was adjusted to investigate the morphology(grain size and film roughness)of the perovskite film.The results show that a suitable amount of FA with large ion radius can promote the formation of large-grain perovskite thin films in pure MA system,but too much FA can easily cause the formation of yellow phase,which has a negative effect on the performance of the device.Finally,the perovskite film based on MA_0.75FA_0.25Pb I₃ component has the best performance,and the corresponding device showed a photoelectric conversion efficiency of 21.2%.(3)Study on performance perovskite film and solar cells fabricated based on interface decoration.The Octylammonium iodide(OAI)molecules are applied to reduce the carrier recombination between the perovskite and hole transport layer.Compared with the base sample,OAI molecules not only contribute to the secondary growth of perovskite grains to improve the film quality,but also reduce the carrier recombination at the interface and increase the V_OCand FF of the device.Finally,the OAI-modified device with an efficiency of 22.6%was successfully obtained,can still maintain 93%of the initial efficiency after 500 hours of continuous illumination in air with humidity of about 30?40%.