One Step Method Of Cleaning Properties Of Perovskite Thin Films Based On Modified Solution

With the rapid economic development, and the rapid expansion of the mo dern society, large amounts of non-renewable resources,e.g., coal and oil,are consu med and wasted.Therefore, new energy industry has become an important part of th e national development strategy.Recently,perovskite solar cells had played an incre asingly important position in new energy technologydue to their simple preparati on and high conversion efficiency. So far, the photoelectric conversion efficiency(PCE) of perovskite solar cells has been close to that of polycrystalline silicon solar cells, and has preliminary reached the requirement of industrialization.Howe ver, the new technology still faces significant obstacles to their effective use,e.g.,low life, easy hydrolysis, instable efficiency, and environmental toxicity.In the present dissertation, we will synthesize perovskite thin films by one-step process and fabricate perovskite solar cells with the inverted structure of planar heterojunctions(i.e., ITO/PEDOT/toluene/SWCNT/PCBM/Al).In addition,we will optimize the parameters of device structure and technological parameter s of preparation to improve the efficiency of the device, reduce the dependence on the environment, and prolong the life of the device. Three main research cont ents will be described as follows:First, we will demonstrate that excess methyl ammonium halide(MAI, CH3NH3I) has a positive effect on the photoelectric properties of perovskite device s. Abundance or shortage of MAI in the films results in the degradation of the photoelectric properties. Sec-butyl alcohol is proved to be a solvent not only suitable for CH3NH3 Pb I3 fast crystallization deposition process, but also for adj usting the amount of MAI in CH3NH3 Pb I3 films.In addition, the influence of s olution concentration of dimethyl sulfoxid(DMSO) on the surface appearance of perovskite thin films is also analyzed. The application of these films to solar cell fabrication yielded an average PCE of 11%, with both flat surface and exc ellent repeatability.Second, we can completely remove the excess MAI by adding a repeat cle an process by toluene. Then, the average PCE of devices can be enhanced up to 12%. Moreover, the process is also beneficial to improve Voc and lower the i mpact of water on the PEDOT film quantity.Finally, we show that a dense cladding layer of single-walled carbon nanot ubes(SWCNTs) in the surface of perovskite devices with optimal parameters will help to significantly increase the device life in high humidity environment.Furthermore, by using the optimal mixing ratios between SWCNTs and toluene,we can remarkable improve the environmental adoptability of perovskite devices, and reduce the negative effects about water-absorbing quality from PEDOT layer on the final device performances.