Triboelectricity usually occurs between two different materials and can be understood as electron transfer in the framework of the electron-cloud model. Recently, experiments have shown that charge transfer also can happen between chemically identical materials but different surface curvatures. To understand the driving mechanism for this case, we carry out, for the first time, first-principles density functional theory (DFT) investigations of charge transfer due to flexoelectricity and piezoelectricity in two-dimensional materials. Case studies of piezoelectric molybdenum telluride (2H–MoTe₂) and non-piezoelectric graphene are analyzed in detail. It is found that a large corrugation of the contacting materials, whether identical or not, causes a nonlinear increase in the charge transfer, leading to electron depletion near concave surfaces and electron accumulation near convex surfaces. The maximum charge transfer is found to occur around an equilibrium separation distance of the contacting materials. In the case of graphene, and different from 2H–MoTe₂, both piezoelectric and flexoelectric coefficients are found to increase as the corrugation increases and is followed by a bandgap opening. We stipulate that the present ab initio findings provide new insight toward understanding the origins of triboelectricity.

摩擦电通常发生在两种不同的材料之间，在电子云模型的框架内可以理解为电子转移。最近，实验表明，在化学相同的材料但表面曲率不同的情况下，电荷转移也可能发生。为了了解这种情况的驱动机制，我们首次进行了第一原理密度泛函理论（DFT）研究二维材料中由于压电和压电引起的电荷转移。压电碲化钼（2H–MoTe _2的案例研究）和非压电石墨烯进行了详细分析。已经发现，无论是否相同，接触材料的大波纹都会导致电荷转移的非线性增加，从而导致凹面附近的电子损耗和凸面附近的电子积累。发现最大的电荷转移发生在接触材料的平衡分离距离附近。在石墨烯的情况下，不同于2H–MoTe ₂，发现压电系数和挠电系数都随波纹的增加而增加，并随后出现带隙开口。我们规定，目前的从头算起的发现为理解摩擦电的起源提供了新的见识。