Fabrication And Photovoltaic Performance Of Mesoscopic Perovskite Solar Cells By Two-step Deposition Method

With the aggravation of energy crisis and environmental pollution problems, people need develop more clean and renewable energy to alleviate these problems urgently. Solar energy is clean and environmental protection with rich resources, and is not affected by geographical factors, which has been regarded as a green energy. Solar energy can effectively reduce the energy crisis and environmental deterioration. Solar cells are probably devices with the most reasonable method effective utilization of solar energy. Perovskite solar cell（PSCs） is a promising solar cell owing to its low cost, simple process and high energy conversion efficiency. In this dissertation, the development status, structure composition, working principle and characterization testing methods of perovskite solar cells（PSCs） were described. The dissertation focused on the preparation and photovoltaic performance of hole-conductor-free perovskite solar cells with carbon electrode. Especially, the impact factors include resistance of compact layer, density and immersion time of Pb I2, and different solvents of CH3NH3 I on the photovolatic performance of the cells were studied, the dissertation provided the basic experimental guideline for the improvement of photovolatic performance in PSCs. The main research contents are as follows:（1） PSCs with different compact layer resistance were prepared. The effect of tight layer resistance on the photovoltaic performance of the cells was also explored. The results showed that the resistance of compact layer between 300 600 Ω was better. It was shown that compact layer had positive effects on transport the electrons and impeded the holes transmission when the value of compact layer resistance was in reasonable range.（2） A series of perovskite layers with different density and immersion time of Pb I2 layer were prepared using two-step deposition method. The effects of density and immersion time of Pb I2 on photovoltaic performance were studied. The results showed that perovskite crystal size was increased with increas ing the immersion time. The results of scanning electron microscope（SEM） confirmed the perovskite coverage increased, when the density and immersion time of Pb I2 continues increasing. It is shown that the higher photoelectric conversion efficiency of PSCs was obtained when the immersion time was 30 min.（3） Isopropanol and butyl alcohol were introduced as a solvent of CH₃NH₃I to fabricate the perovskite. The effect of the morphology and coverage of perovskite crystal on different solvents were studied. It was observed that PSCs prepared by butyl alcohol showed the higher perovskite crystal coverage, more smooth surface, more uniform particle size probably due to the weaker chemical polarity of butyl alcohol compared with isopropanol, so the dissolve ability of perovsk ite with butyl alcohol was weaker than that of isopropanol. And with the immersion time increased, butyl alcohol dissolved fewer perovskite. The photovoltaic performance of PSCs fabricated by the different two solvents was studied, the higher photoelectric conversion efficiency of PSCs was obtained by using butyl alcohol.