Reliable Piezoelectricity in Bilayer WSe2 for Piezoelectric Nanogenerators

Ju Hyuck Lee, Jae Young Park, Eun Bi Cho, Tae Yun Kim, Sang A. Han, Tae Ho Kim, Yanan Liu, Sung Kyun Kim, Chang Jae Roh, Hong Joon Yoon, Hanjun Ryu, Wanchul Seung, Jong Seok Lee, Jaichan Lee, Sang Woo Kim

Research output: Contribution to journalArticlepeer-review


Recently, piezoelectricity has been observed in 2D atomically thin materials, such as hexagonal-boron nitride, graphene, and transition metal dichalcogenides (TMDs). Specifically, exfoliated monolayer MoS2 exhibits a high piezoelectricity that is comparable to that of traditional piezoelectric materials. However, monolayer TMD materials are not regarded as suitable for actual piezoelectric devices due to their insufficient mechanical durability for sustained operation while Bernal-stacked bilayer TMD materials lose noncentrosymmetry and consequently piezoelectricity. Here, it is shown that WSe2 bilayers fabricated via turbostratic stacking have reliable piezoelectric properties that cannot be obtained from a mechanically exfoliated WSe2 bilayer with Bernal stacking. Turbostratic stacking refers to the transfer of each chemical vapor deposition (CVD)-grown WSe2 monolayer to allow for an increase in degrees of freedom in the bilayer symmetry, leading to noncentrosymmetry in the bilayers. In contrast, CVD-grown WSe2 bilayers exhibit very weak piezoelectricity because of the energetics and crystallographic orientation. The flexible piezoelectric WSe2 bilayers exhibit a prominent mechanical durability of up to 0.95% of strain as well as reliable energy harvesting performance, which is adequate to drive a small liquid crystal display without external energy sources, in contrast to monolayer WSe2 for which the device performance becomes degraded above a strain of 0.63%.

Original languageEnglish
Article number1606667
JournalAdvanced Materials
Issue number29
Publication statusPublished - 2017 Aug 4

Bibliographical note

Funding Information:
J.-H.L., J.Y.P., and E.B.C. contributed equally to this work. This work was financially supported by a grant from Basic Science Research Program (2015R1A2A1A05001851) through the National Research Foundation (NRF) of Korea Grant funded by the Ministry of Science, ICT & Future Planning and a grant from the Center for Advanced Soft Electronics (CASE) under the Global Frontier Research Program (NRF–2013M3A6A5073177). Computational resources for DFT simulation were supported by KISTI supercomputing center (KSC-2015-C3-0012).

Publisher Copyright:
© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering


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