On the evening of September 30, Beijing time, Nature, a top international academic journal, published online the joint research progress of Professor Yuan Mingjian's research group from the School of Chemistry of Nankai University and the research group of Professor Edward H. Sargent from the University of Toronto, Canada.
The study is entitled "High-efficiency and thermally stable FACsPbI3 perovskite photovoltaics". The team conducted in-depth research on the problem of insufficient stability of perovskite solar cells under high temperature conditions, and revealed for the first time the complex chemical composition segregation problem inside alloy perovskite films. Based on this, the research team developed a novel in-situ crystallization kinetic control strategy, and successfully fabricated perovskite solar cell devices with high efficiency and high working stability, marking a major technological breakthrough in this field.
Nankai University is the first corresponding unit, and Professor Yuan Mingjian of the School of Chemistry and Professor Edward H. Sargent of the University of Toronto, Canada, are the corresponding authors of the paper.
It is pointed out that the preparation of high-performance perovskite solar cells often needs to rely on methylammonium chloride additives to stabilize the phase and regulate the crystallization. However, this additive is easy to decompose under high temperature conditions, which leads to the imbalance of the chemical composition of perovskite films, which significantly reduces the operation stability of the cell under high temperature conditions, and becomes the main obstacle restricting the commercialization of high-performance perovskite photovoltaics.
FACsPbI3 alloy perovskite has high phase and chemical stability, and theoretically does not need to rely on methylammonium chloride additives, which is the most promising candidate material for high-performance and high-stability perovskite solar cells. However, the performance and stability of FACsPbI3 perovskite solar cells prepared by traditional methods are much lower than those expected in theory, and the reasons need to be further explored. Therefore, it has become an urgent need to promote the further development of perovskite photovoltaic technology by digging deep into the intrinsic structural stability of perovskite photovoltaic materials, understanding the failure mechanism of FACsPbI3 alloy perovskite solar cell devices, and realizing the controllable construction of perovskite solar cell devices with high efficiency and high temperature working conditions.
Figure: Crystallization path transition strategy to achieve high-efficiency, high-temperature, stable FACsPbI3 perovskite solar cells
Prof. Mingjian Yuan's research group has long been committed to the research of high-performance perovskite semiconductor optoelectronic materials and devices. In the process of continuous exploration of new high-stability perovskite material systems, the research group has carried out a large number of time-space resolution in-situ characterization experiments in the early stage by using large scientific devices such as synchrotron radiation light sources, and systematically explored the crystallization kinetics of FACsPbI3 alloy perovskites. Based on the above research, the team revealed for the first time the longitudinal gradient segregation of components in FACsPbI3 alloy perovskites due to the spatiotemporal differences in crystallization behavior, and pointed out that this problem is the key factor leading to the low performance of FACsPbI3 perovskite solar cell devices and the insufficient stability of high-temperature operating conditions.
On this basis, the research group and its partners carried out in-depth theoretical simulation studies to clarify the fundamental causes of the heterogeneity of the spatial components. Subsequently, through rational screening of ligand chemical structure, combined with multi-dimensional in-situ crystallization kinetics study, the research team proposed for the first time a universal crystallization path regulation conversion strategy, and finally realized the controllable preparation of high-quality alphaammonium-free FACsPbI3 perovskite films, which completely solved the problem of spatial component heterogeneity of FACsPbI3 perovskite films. The FACsPbI3 perovskite solar cell devices fabricated by this strategy exhibit world-class energy conversion efficiency and stability at high temperatures. After the authoritative certification of Fujian National Photovoltaic Industry Metrology Center and Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, the steady-state energy conversion efficiency of the device has reached the highest level of formal perovskite solar cells.
Based on the basic discipline of chemistry, this research combines advanced theoretical simulation analysis technology, integrates multidisciplinary research methods such as condensed matter physics and semiconductor devices, successfully realizes a further in-depth understanding of the intrinsic structural properties and structure-activity relationship of perovskite semiconductor materials, and develops new principles and methods for the controllable preparation of key photovoltaic materials for high-quality perovskite thin films, which empowers the development of a new generation of perovskite photovoltaic cell technology.
Li Saisai, Wang Di and Ding Zijin, Ph.D. students in physical chemistry in the School of Chemistry, and Jiang Yuanzhi, a distinguished researcher in the School of Chemistry, are the co-first authors of the paper.
The above research work has been funded by the National Science Foundation for Distinguished Young Scholars, the National Natural Science Foundation of China and other projects, and has also been strongly supported by the National Key Laboratory of Special Chemical Power Sources and the Frontier Science Center for the Creation of New Organic Substances.
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Source: School of Chemistry, Financial Media Center, Nankai University
Editor: Zhang Yu
Review: Yan Jingyun, Zhang Yangzihan, He Sai