Interface Regulation To Obtain Thermally Stable Inverted Perovskite Solar Cells

Perovskite solar cells（PSCs）are promising technologies in the third generation of solar cells due to their high photoelectric conversion efficiency,low cost and convenient manufacturing.However,the thermal stability of perovskite solar cells is still a challenge for industrial development.Improving the thermal stability of perovskite materials plays a key role in improving the thermal stability of PSCs,and great efforts have been made to stabilize perovskite materials,including composition adjustment,crystallization control and interface optimization.Here,we select the PSCs of the inverted FACs system with higher stability as the research object,summarize the use of different kinds of additives to regulate the crystallization and defect passivation of perovskite,and describe the relevant mechanisms.In addition,the influence of different hole transport layers on the thermal stability of inverted PSCs is also discussed.The main research contents are as follows:（1）As a multi group crosslinking agent,amino acid derivatives can contain different kinds of characteristic functional groups and show different characteristics.Aiming at one of the most difficult problems,ionic defects,amino acid derivatives can repair these defects through their multi-functional groups.Known ionic defects（such as organic cations and halogen anions）mostly exist on surface and/or grain boundaries of perovskite films,and amino acid derivatives can coordinate well with defects,so as to obtain high-quality perovskite films.In this work,the effects of two kinds of amino acids（L-arginine and L-glutamic acid）with contrastive isoelectric points（p Is）on perovskite film formation,defect passivation mechanism,device efficiency,flexible substrate and thermal/moisture stability were studied.Efficiency of inverted perovskite solar cells（PSCs）was improved from～20%to nearly 23%with additives for rigid substrate.High p I L-arginine improves V_OC significantly,while low p I L-glutamic acid excels in FF and J_SC.More importantly,low p I L-glutamic acid shows superior thermal and moisture stability,indicating inherent stronger bonding between L-glutamic acid and perovskite.（2）Perovskite films are susceptible to be damaged during its service period due to their weak mechanical properties.Waterborne polyurethane（Ab-WPU）with acylhydrazone bond were employed as a dynamic covalent polymer engineering to construct self-healing perovskite solar cell（APSCs）.In addition to the enhancement of crystallinity,its functional groups to passivate the defects of the perovskite film,And Ab-WPU effectively enhances the flexibility and self-healing property of APSC.The champion efficiency of APSCs on rigid and flexible substrates is 22.43%and 21.27%,respectively.At the same time,their stability has been improved,and the dynamic acylhydrazone bond can repair perovskite crystal defects at 60℃,so that Ab-WPU modified devices can recover to efficiency above 95%by heating after 1000times of bending.This strategy provides an effective method for dynamic self-healing materials in PSCs.