The Stability Of Perovskite Solar Cells

Energy is an important resource for human life.It promotes the development of human civilization and social progress.Solar energy,as an inexhaustible clean energy,has attracted wide attention.In recent years,organic-inorganic hybrid perovskite solar cells have become a hot research area due to their low cost and high conversion efficiency.Perovskite solar cel s have developed rapidly with power conversion efficiency exceeding 23%in less than 10 years,which is close to monocrystalline silicon solar cel s.However,the stability of perovskite solar cells has always been the main bottleneck of their commercialization.In order to improve the stability of perovskite solar cells,the material properties,fabrication process and device structure need to be carefully considered.In this paper,the unstable problems in the fabrication process and the preparation of raw materials are studied from the aspects of crystallization transformation of perovskite films and stability of precursor fluid.Then the reasons of short-term performance variation caused by in-situ interface modification are explored.The main contents of this paper include:1.In-situ transformation and dissolution recrystallization mechanisms are competitive in the process of perovskite film formation.These mechanisms have a great influence on the device performance of perovskite solar cells during the two-step immersion process.Low concentration of iodomethylamine was used to inhibit the dissolution and recrystallization of perovskite?Ostwald ripening growth?in lower polarity mixed solvents?isopropanol/cyclohexane?,and porous PbI₂ was combined with temperature-assisted to effectively promote the transformation from PbI₂ to perovskite.The solution engineering coordinates the effect of complete transformation and dissolution recrystallization of perovskite,thus forming pure perovskite thin films in a short time without any residual PbI₂.This method provides a feasible scheme for rapid preparation of large area perovskite thin films.2.The perovskite precursor usually degrades due to photooxidation,which leads to the deterioration and turbidity of the precursor and hinders the large-scale production of solution method.Based on the principle of reversible chemical reaction,we use tri-iodide ions to stabilize perovskite precursor.The results show that tri-iodide ions can effectively slow down the agglomeration of colloids by reducing the size and distributing uniformly,and improve the quality of perovskite films.When aging time increased to 15 days,perovskite precursor still remained clear,and its power conversion efficiency decreased only from 19%to 16%.The method effectively stabilizes the perovskite precursor and facilitates large-scale solution production.3.According to the short-term variation of perovskite solar cell performance,we carefully studied the factors affecting the short-term stability of the device under different atmospheres,and found that the change of the hole transport layer had a greater impact on the device performance.Further experiments and characterization reveal that the short-term stability of the device is related to additives in the hole transport layer.These additives had a Lewis acid-base interaction with perovskite and formed a complex which regulates the band arrangement and passivates the defects at the interface,resulting in short-term performance variation.It is noteworthy that in-situ interface modification may exist in all perovskite solar cells with similar additives.This study reveals for the first time the short-term stability of perovskite solar cells and provides a boost for their commercialization.