Research On Fabrication And Performance Of Stable All-Inorganic Perovskite Solar Cells

In recent years,the application of organic-inorganic hybrid perovskite materials to the preparation of high-efficiency perovskite solar cells has been rapidly developed.However,the working environment of solar cells cannot avoid high temperature and ultraviolet radiation,which will cause the volatilization of organic components and greatly reduce the performance of the material.Therefore,the contradiction between the properties of materials and the working environment of the solar cells hindered its development.The excellent photovoltaic properties and stability of CsPbX3 materials make it a photovoltaic material with great development potential.Studies have shown that all-inorganic CsPbX3 materials without organic components have better component stability,and CsPbX3 based solar cells are suitable for preparing tandem cells in series with silicon solar cells,which broadens its application range.However,the performance of the all-inorganic perovskite solar cell prepared by the existing technical means is still difficult to achieve the goal of practical application.Finding suitable ways to improve the photovoltaic performance of all-inorganic CsPbX3 has also become a research hotspot in the field.This study aims to further improve the performance of all-inorganic CsPbX3 devices through strategies such as additive engineering,component engineering,and preparation process optimization,and to illustrate the mechanism of performance improvement in combination with test and characterization methods.In this study,hydrobromic acid was added to the CsPbI3 precursor,the film was deposited by a one-step deposition method,and annealed in a low temperature environment to obtain a CsPbI3 film that can absorb visible light.Studies have shown that hydrobromic acid can not only reduces the phase transition temperature and realizes the low-temperature preparation of thin films,but also induce the formation of high-quality perovskite films with mixed phases.Finally,all-inorganic CsPbI3 based solar cells with superior photovoltaic performance and phase stability were prepared.In addition to the intrinsic phase stability,defects in the perovskite surface and bulk are likely to become the binding sites of water and oxygen in the environment,causing material degradation and devices performance decrease.This paper further proposes that using non-ionic polymers Polyethyleneimine as a bi-functional additive to improve the photovoltaic performance of all-inorganic CsPbI2Br perovskite solar cells.The large amount of amino groups contained in Polyethyleneimine synergistically interact with metal ions and halogen ions and form chemical bonds,which significantly passivate the defects of the film.At the same time,as a macromolecular long-chain compound,the long-chain molecules remain at the grain boundaries after annealing,which induces the perovskite film to change from hydrophilic to hydrophobic,thereby improving its long-term stability.In the end,under the combined effect of passivation defects and improved hydrophobicity,CsPbI2Br-based films and solar cells performed extremely well humidity stability in different humidity environments and the best power conversion efficiency of the solar cells has also reached a higher level of the CsPbI2Br-based perovskite solar cells.In general,after repeated exploration and experimental verification,this research puts forward several strategies for comprehensively improving the photovoltaic performance of CsPbX3 perovskite solar cells.First,the CsPbI3 perovskite film based mixed-phases was prepared at low temperature by using hydrobromic acid,and a flat-plate structure all-inorganic perovskite solar cells was further prepared.The performance of thin films and devices prepared by hydrobromic acid at low temperature were evaluated and the mechanism of the mixed phase to improve stability was explained in detail.Secondly,the use of non-ionic polymer passivates the defects of the CsPbI3Br perovskite film,at the same time,the non-ionic polymer wraps the perovskite crystal grains and induces the formation of smaller crystal grains while improving the hydrophobic properties of the film.Under the combined effect of non-ionic polymers to passivate defects,reduce surface energy and increase hydrophobicity,the photovoltaic performance and stability of CsPbI2Br-based solar cells have been significantly improved.The above two methods provide strategies and possibilities for further realizing the substantial improvement and market applications of the performance of all-inorganic perovskite solar cells.