Structural Design And Interface Passivation In Perovskite Solar Cells

Energy is a booster for the development of human civilization.With the continuous development of human society,the demand for energy is increasing.Due to the limited reserves of coal and oil,it is not renewable and pollutes the environment.Therefore,it seeks an efficient renewable energy source.The application has become a research hotspot in today's society.At present,solar energy has been given great hope as a renewable,easy-to-use and environmentally friendly renewable energy source.Therefore,from 2009 to 2019,in a few years,the research on metal halide perovskite solar cells based on organic-inorganic hybridization has made great progress,and its photoelectric conversion efficiency has increased from 3.8%to23.7%.It has been comparable to silicon-based solar cells that have been commercialized on the market.Due to the huge leap in photoelectric conversion efficiency,instead of silicon-based solar cells,it is possible to make a new generation of solar cells with low cost,high efficiency and long life truly enter people's lives.In addition,due to the limitations of the special structure and preparation method of perovskite materials,the stability is relatively poor,which also restricts the further improvement of the efficiency of the perovskite battery and the commercialization.Therefore,the main research topic of our second paper is to overcome the stability of the perovskite solar cell and prepare the light absorbing layer.We have done the following work:?1?Titanium dioxide TiO₂ is the most widely used electron transport material for perovskite solar cells.Its application can greatly improve the efficiency of electron extraction.Its unique valence band position can effectively block the transfer of holes to the cathode,but he also has its Disadvantages,under the long-term ultraviolet light irradiation,the oxygen vacancies formed on the surface will form an electron pair with the iodine anion of the perovskite material,which easily causes decomposition degradation of the perovskite material.As a large family of chemical elements,rare earth ions can effectively block and convert ultraviolet light,fully utilize the down-conversion luminescence ability of rare earth ions and the energy transfer between suitable rare earth ions.Sm³⁺and Eu³⁺co-doped TiO₂ are designed and designed.The electron transfer layer greatly improves the stability and photoelectric conversion efficiency of the planar CH₃NH₃PbI₃ perovskite solar cell.?2?The preparation of conventionally prepared TiO₂ requires a high temperature of 500?,which greatly affects the development of perovskite solar cells in flexible substrates.Based on this factor,pulsed laser deposition technology is applied to the preparation of Sm³⁺and Eu³⁺co-doped TiO₂ electron transport layer.Compared with the method of preparing electron transport layer,pulsed laser deposition technology is simple to prepare,the film quality is better,and large area is prepared efficiently.In the device,by optimizing the doping concentration of rare earth elements,the perovskite solar cell achieved a photoelectric conversion efficiency of 19.01%,and in addition,the photoelectric conversion efficiencies of the large area?225mm²?and the flexible device were 12.60%and 15.48%,respectively.In addition,benefiting from the excellent light conversion capability of rare earths,perovskite solar cells can maintain more than 80%of the original efficiency within 25 days of complete daylight exposure or after 100 hours of UV irradiation.?3?The selection of perovskite materials is very important.However,perovskite solar cells with CH₃NH₃PbI₃ as the light absorbing layer are easily degraded in the surrounding environment due to thermal instability and the inherent volatility of organic components,and the stability is poor.This is a major obstacle to commercialization.In order to solve these problems,an effective method for improving thermal stability is to use a strongly stable inorganic Cs cation instead of a fragile organic group.Compared with organic-inorganic hybrid perovskites,inorganic perovskites?CsPbX₃,X=I,Br,Cl or mixtures?exhibit multicolor,excellent light stability and high heat due to the removal of unstable organic cationic groups.stability.Even if the temperature exceeds 300 degrees,there is a certain photoelectric conversion efficiency.Therefore,in recent years,all-inorganic perovskite solar cells have been intensively focused on photovoltaic devices.Recently,inorganic CsPbIBr₂perovskite solar cells?PSCs?have received great attention due to their thermal stability,bright photovoltaic properties,and unique colors.However,the low power conversion efficiency and humidity instability of CsPbIBr₂ PSC remains a challenge because the perovskite grain boundary quality is poor and the surface causes non-radiative charge carrier recombination,which limits open circuit voltage(V_OC)and power conversion.Efficiency?PCE?perovskite solar cells.In this work,we used several different anti-solvents to optimize the morphology of the CsPbIBr₂ crystal,and then further enhanced the growth of CsPbIBr₂ crystals using organic molecular sulfonium salts,which effectively reduced electron recombination and achieved more than 9%long-term stable PCE.In addition,the PCE of CsPbI₂Br and CsPbI₃perovskite solar cells reached 10.73%and 6.91%,respectively,with the help of large ruthenium?GA?passivation and antisolvent.In addition,large areas?15×15 mm²?and flexible batteries were further explored.This work shows that surface passivation is an effective method to improve photovoltaic performance and excellent stability.