Fabrication And Performance Optimization Of Efficient Perovskite Solar Cells Based On Additive Engineering

In recent years,human society has an increasing demand for energy,while the use of traditional fossil energy has also led to resource depletion and environmental pollution,so the development of green and renewable energy is imperative,in which solar energy has been widely concerned because of its series of advantages.Perovskite photovoltaic technology has become an emerging technology in the photovoltaic field because of its rapidly improved efficiency,simple preparation process and low cost.However,there are still some problems in perovskite solar cells,such as poor long-term stability and low photoelectric conversion efficiency.In the structure of perovskite solar cells,the perovskite layer is a crucial part affecting the performance of the cell,and the defects in the perovskite are an important factor affecting the quality of the perovskite layer.Generally,there are various crystal defects in perovskite,such as cation defects,anion defects,etc.The existence of these defects and the crystallinity of perovskite will seriously affect the quality of perovskite thin films.These defects will also become non-radiative recombination sites,seriously affecting the photoelectric conversion efficiency and long-term stability of perovskite solar cells.Therefore,how to effectively passivate defects and obtain high-quality perovskite films is the key to the preparation of high-efficiency perovskite solar cells.Additive engineering is a simple and efficient strategy to optimize the battery performance.Additives are introduced into perovskite films to improve the nucleation and crystallization of perovskite and passivate perovskite defects through the interaction between additives and perovskite.In this work,we use additive engineering to improve the perovskite layer and optimize the performance of perovskite solar cells.（1）A additive,methyl 3-aminothiophene-2-carboxylate（MATC）,was introduced into the perovskite film by dissolving it into the anti-solvent chlorobenzene in an anti-solvent manner,and the Cs-FA-based perovskite solar cell device with a trans-planar structure was prepared simultaneously.Through a series of characterization and testing,it is found that the crystallinity of the perovskite thin film is stronger and the grain size is also increased after the introduction of MATC into the perovskite layer.The groups on MATC can interact strongly with perovskite and passivate the defects in perovskite,which greatly reduces the density of defect States,inhibits non-radiative recombination,prolongs the carrier lifetime and enhances the charge transport performance.The device performance of the perovskite solar cell prepared by the method is greatly improved compared with the device performance without using the additive,the photoelectric conversion efficiency has increased from 19.67%to 21.51%,and the hysteresis phenomenon is also inhibited.At the same time,the long-term stability of the unpackaged device was measured under different conditions,and the modified device benefited from the defect passivation of perovskite,and its long-term stability performance was better than that of the control device.The additive provides a reference way for the preparation of high-performance perovskite solar cells.（2）A imidazolium salt additive 1-carboxymethyl-3-methylimidazolium chloride（CMC）was used.A proper amount of the additive is directly dissolved in a precursor solution of the perovskite,so that the additive is introduced into a perovskite layer and a high-efficiency Cs-FA-based perovskite solar cell device with a trans-planar structure is realized.It is found that the groups（imidazole and carboxyl）in the additive can coordinate with the undercoordinated Pb²⁺in the perovskite,and there is electrostatic interaction between the imidazole cation and the perovskite anion,which greatly inhibits the generation of defects,and at the same time,the perovskite film with better crystallinity,larger and fuller grain size is obtained.The higher quality perovskite thin film also brings better performance to the perovskite solar cell device.After the introduction of CMC,the photoelectric conversion efficiency has increased from19.56%to 21.70%,which is a very significant improvement,and the hysteresis phenomenon is also improved.The passivation of the defects and the enhancement of the hydrophobicity also enable the prepared device to better resist the corrosion of water and oxygen,and the unpackaged device also shows good long-term stability.The additive is more efficient and more convenient to use,has great application potential in the aspect of preparing high-performance perovskite solar cell devices,and provides reference value for the promotion and commercialization of perovskite solar cells.