Chemi‐Mechanically Peeling the Unstable Surface States of α‐FAPbI3

• Published in: Small (Weinheim an der Bergstrasse, Germany) Vol. 18; no. 46; pp. e2204742 - n/a
• Main Authors: Liang, Zihui, Jin, Bowen, Cao, Jinguo, Chen, Fengxiang, Li, Jing, Wang, Shimin, Wang, Kai, Wu, Congcong
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 17.11.2022
• Subjects: High temperature; Hydrophobicity; Kapton (trademark); Lattice strain; Nanotechnology; Peeling; Perovskites; Phase stability; Phase transitions; Polyimide resins; Relative humidity; siliconization; stability; Surface defects; Surface properties; tape peel; α‐FAPbI 3
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.202204742

Surface states are one of the crucial factors determining the phase stability of formamidinium‐based perovskites. Compared with other compositions, exclusive lattice strain in FAPbI3 perovskite generates defects at the surface more readily, making them more vulnerable at the surface and easier to trigger the phase transition from α‐phase to the non‐perovskite δ‐phase. In order to regulate the surface quality, here, a chemi‐mechanical cleavage approach is reported, i.e., tape peel‐zone (PZ), implemented by attaching and peeling off the ordinary Kapton Tapes. The PZ approach can simultaneously eliminate the surface defects of perovskite and siliconize the film surface with hydrophobic silicone compounds. These two functionalities endow α‐FAPbI3 perovskite with a robust hydrophobic surface, which can sustain for 30 days under a relative humidity of 60% and withstand the high temperature up to 240 °C. The unencapsulated PZ‐treated cells show 80.3% of initial performance after 90 h of continuous operation in ambient air, which is 31.4 times more stable than the pristine cell. A micromechanical cleavage approach, termed as tape peel‐zone (PZ), is implemented by attaching and peeling off the ordinary Kapton Tapes from the perovskite surface. The PZ approach can dually eliminate the surface defects and siliconize the perovskite surface by the reciprocal atomic exchange, which provides a generic method that can deliver both high stability and photovoltaic performance for perovskite solar cells.