Blade-coating Based Fabrication Of Perovskite Films And Manipulation On The Crystallization Process

With development of human society and economy,people’s living needs and social productive activities are increasingly demanding for more energy.However,with the depletion of fossil fuels and the side effects such as environmental pollution brought about by the burning of fossil fuels,the current non-renewable energy sources cannot only meet the social development needs but also become one of the social potential destabilizing factors.Therefore,the development of clean and highly efficient renewable energy and energy storage technologies has become a strategic high ground for science and technology and a decisive strategic focus for many countries in the world today.Among all green energy sources,solar energy has long-term development space due to its huge reserves,environmental protection,and convenience.At present,after several generations of development of solar cells,from the first generation of crystalline silicon solar cells to the second generation of amorphous silicon thin film solar cells,to the third generation of laminated thin film solar cells,the efficiency of its devices continue to increase,The raw material and structure of the cell are continuously optimized.Among them,perovskite solar cells stand out due to their advantages of thinness,high efficiency,simple preparation process,and controllable cost,and are currently receiving much attention.The organic-inorganic hybrid perovskite is also regarded as another star after graphene,and was named one of the top ten technological breakthroughs of 2013 by Science.In less than eight years,it has increased its efficiency from 3.8%to more than 22%,and spent eight years walking through crystal silicon solar cells over twenty years.However,perovskite solar cells still have some problems to be solved,such as instability,toxicity of materials,and large-area preparation difficulties.In this paper,the perovskite solar cell device that can be mass-produced with high efficiency and stability can be realized by including,without being limited to the above problems,a process optimization and the introduction of a physical regulation crystal growth method.The specific research work is as follows:(1)Fabrication of perovskite thin-films and evaluation of the quality of the corresponding films.As we known,perovskite light-absorbing layer is an important part of perovskite solar cells and is directly related to the performance of devices.In this step of part of the paper,we independently designed and built a blade-coating equipment and brush coating platform.By exploring the blade coating process and continuously improving the structure of the brush head,a bright and smooth surface was prepared by the brush coating method under the conditions of automatic preparation and precise positioning.The perovskite crystal film,which is superior in light-absorption performance and a mass-obsessed film,were prepared by a balde coating.Finally,combined with the spin-coating method,these three kinds of technology were then analyzed and summarized.Moreover,the internal mechanism principle was explored to provide reference and guidance for the future perovskite fabrication.(2)Study on growth mechanism of perovskite during blade coating based on solvent engineering.Solvent engineering is widely used to prepare perovskite films by spin-coating,but there are few solvent-engineering studies based on the blade coating method.In this part of the study,we employed solvents such as NMP,DMSO,DMF and GBL to control the growth of the perovskite film during doctor-coating process.By studying the effect of these solvents on the morphology and crystallinity of perovskite films,we systematically summarized the solvent engineering.In addition,with preliminary understanding the mechanism of solvent engineering,we try to solve the problem of area limitation in the preparation of perovskite films by this theory.By controlling the nucleation process of the perovskite,a perovskite film with a smooth,dense,and high degree of crystallinity under a large area is prepared.A further breakthrough in efficiency has been achieved in the assembled large-area perovskite devices.(3)Research on the growth mechanism of perovskite thin-films reduced by rotating magnetic fields.Although the quality of perovskite fabricated by the spin coating is easy to control,there are defects that cannot fabricate perovskite in large areas.However,the blade coating,without this limitation,is still difficult to regulate the growth of perovskite crystals during the fabrication.In this part of the study,we used a rotating magnetic field to regulate the growth of the perovskite crystal.By studying the mechanism of the rotating magnetic field on the crystallization process of the perovskite crystal and its influence,a perovskite thin-film with dense,controllable,high quality was prepared.On this basis,by studying the effect of this type of perovskite crystal film on the corresponding device,we obtained a perovskite solar cell with an efficiency of more than 17.5%and a good stability by balde coating,which has only an approximate loss of 5%when stored in the air for more than 70 days.