SIM-RUC
Surface & Interface Modeling
for Emerging Nanomaterials and Devices

Realizing nearly-free-electron like conduction band in a molecular film through mediating intermolecular van der Waals interactions

Xingxia Cui1†, Ding Han1†, Hongli Guo1†, Linwei Zhou2, Jingsi Qiao2, Qing Liu1, Zhihao Cui1, Yafei Li1, Chungwei Lin3, Limin Cao1, Wei Ji2*, Hrvoje Petek4*, Min Feng1,5*

1 School of Physics and Technology and Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education, Wuhan University, Wuhan 430072, China
2 Beijing Key Laboratory of Optoelectronic Functional Materials & Micro-Nano Devices, Department of Physics, Renmin University of China, Beijing 100872, China
3 Mitsubishi Electric Research Laboratories, 201 Broadway, Cambridge, MA 02139, USA
4 Department of Physics and Astronomy and Pittsburgh Quantum Institute, University of Pittsburgh, Pittsburgh, PA 15260, USA
5 Institute for Advanced Study, Wuhan University, Wuhan 430072, China
†These authors contributed equally to this work.
*Corresponding author. Email: wji@ruc.edu.cn (W.J.); petek@pitt.edu (H.P.); fengmin@whu.edu.cn (M.F.)

DOI:    Publication Date: 


Abstract:

Collective molecular physical properties can be enhanced from their intrinsic characteristics by templating at material interfaces. Here we report how a black phosphorous (BP) substrate concatenates a nearly-free-electron (NFE) like conduction band of a C60 monolayer. Scanning tunneling microscopy reveals the C60 lowest unoccupied molecular orbital (LUMO) band is strongly delocalized in two-dimensions, which is unprecedented for a molecular semiconductor. Experiment and theory show van der Waals forces between C60 and BP reduce the inter-C60 distance and cause mutual orientation, thereby optimizing the π-π wave function overlap and forming the NFE-like band. Electronic structure and carrier mobility calculations predict that the NFE band of C60 acquires an effective mass of 0.53–0.70 me (me is the mass of free electrons), and has carrier mobility of ~200 to 440 cm2V−1s−1. The substrate-mediated intermolecular van der Waals interactions provide a route to enhance charge delocalization in fullerenes and other organic semiconductors.


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View: Nature Communications  10, 3374 (2019)    

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