Pressure‐Suppressed Carrier Trapping Leads to Enhanced Emission in Two‐Dimensional Perovskite (HA)2(GA)Pb2I7

• Published in: Angewandte Chemie International Edition 2020-09, Vol.59 (40), p.17533-17539
• Main Authors: Guo, Songhao, Zhao, Yongsheng, Bu, Kejun, Fu, Yongping, Luo, Hui, Chen, Mengting, Hautzinger, Matthew P., Wang, Yingqi, Jin, Song, Yang, Wenge, Lü, Xujie
• Format: Article
• Language: English
• Subjects: 2D halide perovskites; carrier trapping; Compression; Decompression; Emissions; Energy gap; high-pressure chemistry; Irradiation; Perovskites; phase transitions; photoluminescence enhancement; Pressure; Pressurization; Trapping
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202001635

A remarkable PL enhancement by 12 fold is achieved using pressure to modulate the structure of a recently developed 2D perovskite (HA)2(GA)Pb2I7 (HA=n‐hexylammonium, GA=guanidinium). This structure features a previously unattainable, extremely large cage. In situ structural, spectroscopic, and theoretical analyses reveal that lattice compression under a mild pressure within 1.6 GPa considerably suppresses the carrier trapping, leading to significantly enhanced emission. Further pressurization induces a non‐luminescent amorphous yellow phase, which is retained and exhibits a continuously increasing band gap during decompression. When the pressure is released to 1.5 GPa, emission can be triggered by above‐band gap laser irradiation, accompanied by a color change from yellow to orange. The obtained orange phase could be retained at ambient conditions and exhibits two‐fold higher PL emission compared with the pristine (HA)2(GA)Pb2I7. A remarkably enhanced emission (by 12‐fold) is achieved using pressure to modulate the structure of a highly distorted 2D halide perovskite (HA)2(GA)Pb2I7. In situ structural, spectroscopic, and theoretical analyses reveal that lattice compression under a mild pressure within 1.6 GPa considerably suppresses the carrier trapping, leading to the significantly improved performance.