Strongly enhanced electromechanical coupling in atomically thin transition metal dichalcogenides
Strongly enhanced electromechanical coupling in atomically thin transition metal dichalcogenides
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DOI：
10.1016/j.mattod.2020.12.021
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发表时间：
2021-08-19
期刊：
影响因子：
24.2
通讯作者：
Nam, SungWoo
中科院分区：
文献类型：
--
作者：
Haque, Md Farhadul;Snapp, Peter;Nam, SungWoo
薄膜中的挠曲电由于其吸引人的标度律和普遍存在性而成为一种有效的机电响应。然而，目前的研究表明，有限的面外匡威挠曲电效应（CFE）的超薄过渡金属二硫属化物（TMD）相比，其传统的面内压电响应。在这里，我们报告的原子薄的TMDs，如二硫化钼（MoS 2）和二硒化钨（WSe 2），超过其固有的面内piezoresponses的匡威flexoresponses。我们的压电响应力显微镜（PFM）的测量结果显示，强烈增强CFE的原子级薄的二硫化钼和WSe 2比他们的散装对应物（类似于700%的增强二硫化钼，类似于400%的增强WSe 2）。我们观察到一个异常的减少，在单层结构中的匡威flexoresponse归因于一个puckering变形。通过诱导一个内置的面内张力，以减少起皱，我们估计单层WSe 2的CFE为8.14 pm/V，原子级薄的TMD中最高的。
Flexoelectricity in thin films has emerged as an effective electromechanical response owing to appealing scaling law and universal existence. However, current studies show limited out-of-plane converse flexoelectric effect (CFE) of ultra-thin transition metal dichalcogenides (TMDs) when compared to their conventional in-plane piezoresponse. Here, we report converse flexoresponse of atomically thin TMDs such as molybdenum disulfide (MoS2) and tungsten diselenide (WSe2) which exceeds their intrinsic in-plane piezoresponses. Our piezoresponse force microscopy (PFM) measurements revealed strongly enhanced CFE of the atomically thin MoS2 and WSe2 than their bulk counterpart (similar to 700% enhancement in MoS2, similar to 400% enhancement in WSe2). We observed an anomalous reduction in converse flexoresponse in the monolayer structure attributed to a puckering deformation. By inducing a built-in in-plane tension to reduce puckering, we estimated the CFE of monolayer WSe2 to be 8.14 pm/V, the highest among the atomically thin TMDs.