| In order to meet the growing energy demand of mankind and alleviate the energy crisis and environmental pollution problems,the most promising clean energy solar energy has received widespread attention from humans.Solar cells are one of the most effective ways to use solar energy,which can directly absorb solar energy and convert it into electricity.CH3NH3PbI3 with a band gap of about 1.5 eV,which is an ideal solar cell light absorbing layer material.Its absorption edge is about 800 nm,which can absorb almost all wavelengths of light in the visible range.CH3NH3PbI3 perovskite solar cells have many advantages,such as simple preparation process,low production cost,high photoelectric conversion efficiency,etc.These advantages have made perovskite solar cells attracted extensive attention in the field of solar cells.In this paper,the photovoltaic performance of solar cells was improved by optimizing the CH3NH3PbI3 perovskite layer of solar cells.X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(HR.TEM),X-ray photoelectron spectroscopy(XPS),UV-vis absorption spectroscopy(UV-vis),fluorescence emission(PL)were used to analyze the perovskite layer,and J-V measurement was used to characterize the photovoltaic performance of solar cells.The main research work is as follows:(1)Firstly,a ZnO-based perovskite solar cell and a TiO2-based perovskite solar cell were prepared by a two-step sequential deposition method.The research showed that the photoelectric conversion efficiency of the ZnO-based solar cell prepared by the two-step method is 4.2%,which is 1.28 times of the photoelectric conversion efficiency(3.27%)of the TiO2-based solar cell.This is because the coverage of the perovskite film deposited on the surface of ZnO is higher.On this basis,the perovskite layer of the ZnO-based solar cell was optimized by opropanol-n-hexane mixed solvent.The mixed solvent inhibited the Oswald ripening process during the growth of perovskite grains and improved the homogeneity and compactness of the perovskite film.When the concentration of the CH3NH3I mixed solution was 1 mg/ml,the photoelectric conversion efficiency of the perovskite solar cell reached 6.20%.It was about 1.48 times that of the unoptimized ZnO-based solar cell.(2)Secondly,ZnO-based perovskite solar cells and Ti02-based perovskite solar cells were prepared by one-step spin coating method,and the morphology of the perovskite film and the performance of solar cells were discussed.It was found that the perovskite film prepared on the surface of TiO2 with better compactness and lower defect state than the perovskite film prepared on the surface of ZnO.In addition,the photoelectric conversion efficiency of the Ti02-based solar cell prepared by the one-step method was 5.00%,which was about 1.15 times that of the ZnO-based solar cell efficiency(4.36%).(3)Finally,the perovskite layer was optimized by one-step spin coating using CdS.Studies confirmed that the addition of CdS into the precursor solution would be involved in the perovskite reaction,and a small amount of PbS is formed in the precursor solution.As the defect state of the perovskite layer was inactivated by CdS and PbS can be used as a heterogeneous nucleation site for CH3NH3PbI3,after the incorporation of CdS into the precursor solution,the compactness of the perovskite film was significantly improved.The photoelectric conversion efficiency of the perovskite solar cell without CdS was 4.63%,after the incorporation of CdS,the efficiency of the solar cell reached 6.01%with a high fill factor of 0.63.The above researches showed that the use of mixed solvents in a two-step sequential deposition method can improve the photovoltaic performance of solar cells.Since the one-step spin coating method with the advantage of high precursor conversion rate,the photovoltaic performance of the solar cell prepared by the method is superior to that of the solar cell prepared by the two-step sequential deposition method.The performance of the solar cell can be optimized by adjusting the composition of the one-step spin coating precursor solution.These studies will provide references for the application and production of perovskite solar cells. |
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