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
Department of Chemistry, National University of Singapore, Singapore, Singapore.
Center for Advanced 2D Materials and Graphene Research Centre, Singapore, Singapore.
Nat Commun. 2020 Oct 30;11(1):5483. 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 cmVs between 1.7 to 200 K. Scanning tunneling spectroscopy studies reveal layer-dependent tunneling barrier and domain size on few-layered Ruddlesden-Popper perovskite.
准二维钙钛矿因其固有的稳定性，已成为光电子学领域的一种新型材料平台。器件性能的一个主要瓶颈是其基面上有机分子层导致的高电荷注入势垒，因此目前性能最佳的器件依赖于边缘接触。在此，通过利用二维Ruddlesden-Popper钙钛矿与石墨烯之间的范德华耦合和能级匹配，我们表明平面接触的钙钛矿与石墨烯界面在电荷注入方面呈现出比金更低的势垒。随着偏压增加，电子通过界面的隧穿经由一种栅极可调的、从直接隧穿到场发射的机制发生，并且光致电荷转移在飞秒时间尺度（约50 fs）发生。使用石墨烯接触在分子级薄的Ruddlesden-Popper钙钛矿上制备的场效应晶体管在1.7至200 K之间表现出0.1至0.018 cm²V⁻¹s⁻¹的电子迁移率。扫描隧道谱研究揭示了少层Ruddlesden-Popper钙钛矿上与层相关的隧穿势垒和畴尺寸。
