Electron tunneling at the molecularly thin 2D perovskite and graphene van der Waals interface

• Published in: Nature communications 2020-10, Vol.11 (1), p.5483-5483, Article 5483
• Main Authors: Leng, Kai, Wang, Lin, Shao, Yan, Abdelwahab, Ibrahim, Grinblat, Gustavo, Verzhbitskiy, Ivan, Li, Runlai, Cai, Yongqing, Chi, Xiao, Fu, Wei, Song, Peng, Rusydi, Andrivo, Eda, Goki, Maier, Stefan A., Loh, Kian Ping
• Format: Article
• Language: English
• Subjects: 132/122; 140/125; 147/138; 147/3; 639/301/1005/1007; 639/766/36/1122; 639/925/927/1007; Basal plane; Coupling (molecular); Electron tunneling; Energy levels; Field effect transistors; Field emission; Graphene; Humanities and Social Sciences; Injection; multidisciplinary; Optoelectronics; Organic chemistry; Perovskites; Science; Science (multidisciplinary); Semiconductor devices; Spectroscopy
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-020-19331-6

Quasi-two-dimensional perovskites have emerged as a new material platform for optoelectronics on account of its intrinsic stability. A major bottleneck to device performance is the high charge injection barrier caused by organic molecular layers on its basal plane, thus the best performing device currently relies on edge contact. Herein, by leveraging on van der Waals coupling and energy level matching between two-dimensional Ruddlesden-Popper perovskite and graphene, we show that the plane-contacted perovskite and graphene interface presents a lower barrier than gold for charge injection. Electron tunneling across the interface occurs via a gate-tunable, direct tunneling-to-field emission mechanism with increasing bias, and photoinduced charge transfer occurs at femtosecond timescale (~50 fs). Field effect transistors fabricated on molecularly thin Ruddlesden-Popper perovskite using graphene contact exhibit electron mobilities ranging from 0.1 to 0.018 cm 2 V −1 s −1 between 1.7 to 200 K. Scanning tunneling spectroscopy studies reveal layer-dependent tunneling barrier and domain size on few-layered Ruddlesden-Popper perovskite. Insulating molecular layers on the basal plane of 2D perovskite is a major bottleneck for charge injection that limiting device performance. Here, the authors show that plane-contacted graphene functions as a low barrier and gate-tunable contact to overcome this limitation.