Kinetics And Performance Optimization Of Planar Heterojunction Perovskite Solar Cells

At present,the society is developing rapidly.The energy crisis is also getting worse.In order to solve the energy crisis,it is necessary to find a renewable energy source.As a renewable energy source,solar cells have the opportunity to become an alternative oil in the future.Organic-inorganic hybrid perovskite solar cells?PSCs?have developed rapidly in recent years.Because PSCs have the advantages of low production cost,simple preparation method,and high theoretical photoelectric conversion efficiency?PCE?.Since 2009,the PCE of PSCs has been increasing,but there are still many problems.The growth of perovskite grains is particularly important for the cells.The surface smooth perovskite has a high absorbance and can effectively increase the PCE.In this paper,the growth mechanism of perovskite grains was studied.The quality of the perovskite film is improved by controlling the growth of the perovskite grains.Research results are as follows:?1?To investigate the effect of dimethyl sulfoxide?DMSO?on the crystallization of lead iodide?PbI₂?,planar PSCs devices were prepared by a two-step process.The quality of the perovskite surface film is improved by controlling the crystallization of PbI₂.This improves the optoelectronic performance of PSCs devices.Different crystallinity of PbI₂ was prepared by adjusting the concentration of DMSO in a PbI₂/N,N-dimethylformamide?DMF?solution.The PbI₂ reaction obtains perovskite grains.As the DMSO concentration increases,PbI₂ forms a coordination with DMSO.The crystallinity of PbI₂ is weakened,and the crystallinity of perovskite is increased,which is beneficial to improve the photovoltaic performance of the perovskite layer.X-ray diffraction?XRD?and photoluminescence?PL?spectra were tested.The results show that the quality of the perovskite film is optimal when the DMSO content in the solvent is 10%.The best cell has a photoelectric conversion performance?PCE?of up to 16.89%,an open circuit voltage?Voc?of 1.06 V,a short circuit current?Jsc?of 22.62 mA cm^-2,and a fill factor?FF?of 70.16%.?2?Planar PSCs devices were prepared by a two-step process.The PbI₂substrate was immersed in a mixed ion solution?FAI?MABr?MACl=60mg?6 mg?6 mg?and the effect of immersion time on the photovoltaic performance of the cell was investigated by testing the structure,morphology and physical properties of the perovskite film.The amount of electron holes generated by perovskites was statistically investigated by testing PL.The test results show that,after PbI₂ is immersed in the mixed ion solution,the lifetime of electron holes increases,and the rate of decay is significantly reduced.Compared to samples immersed in pure MAI solution,the band gap of the sample immersed in the mixed ion solution became small and the absorbance is red shifted.Studies have shown that as dipping time is extended,the photovoltaic performance of scells will continue to decline.The best cell is prepared by immersion time for 5s.The best cell has a PCE of 16.56%,a Voc of 1.04 V,a Jsc of 21.66 mA cm^-2,and an FF of 73.1%.?3?The effect of mixed steam annealing on the growth of perovskite crystals was investigated.According to the Ostwald effect,the surface of the perovskite crystals gradually merges.This reduces the holes in the grain surface.Larger grain size perovskite films can be prepared by mixed steam annealing.The quality of the perovskite film is improved and the grain surface defects are reduced.Observe the effect of the solvent on the grain growth of the perovskite surface by using different ratios of mixed solvents.After a proper ratio of mixed steam treatment,the surface smoothness of the perovskite grains is improved.Planar PSCs devices were prepared by using a one-step process.Studies have shown that the best cell is obtained with a DMSO/CB ratio of 1?20.The best cell has a PCE of 18.4%,a Voc of 1.13 V,a Jsc of 23.35mA cm^-2,and an FF of 70.94%.