Piezoelectricity across 2D Phase Boundaries

Abstract

Piezoelectricity in low‐dimensional materials and metal–semiconductor junctions has attracted recent attention. Herein, a 2D in‐plane metal–semiconductor junction made of multilayer 2H and 1T′ phases of molybdenum(IV) telluride (MoTe2) is investigated. Strong piezoelectric response is observed using piezoresponse force microscopy at the 2H–1T′ junction, despite that the multilayers of each individual phase are weakly piezoelectric. The experimental results and density functional theory calculations suggest that the amplified piezoelectric response observed at the junction is due to the charge transfer across the semiconducting and metallic junctions resulting in the formation of dipoles and excess charge density, allowing the engineering of piezoelectric response in atomically thin materials.

Piezo‐Photocatalytic Synergy in BiFeO3@COF Z‐Scheme Heterostructures for High‐Efficiency Overall Water Splitting

“…As manifested in Figure 3g–i, it can be revealed a surface potential of 61.3 mV in the dark, which reduces to 47.2 mV after light irradiation. These results can be attributed to the existence of the built‐in electric field and the dipoles formed by the charge transfer in BiFeO 3 @TpPa‐1‐COF, [31] contributing to the piezo‐induced polarization charge partially depleted by photo‐generated carriers, which is beneficial to the separation of photo‐generated charges and the improvement of catalytic activity.…”

Synergistic Enhancement of Photocatalytic CO2 Reduction by Built‐in Electric Field/Piezoelectric Effect and Surface Plasmon Resonance via PVDF/CdS/Ag Heterostructure

“…The enhanced piezoelectric properties of PVDF/CdS/Ag under light produced more polarized charges, which promoted the separation of photogenerated carriers. [ 70 ] In addition, the surface potential of PVDF/CdS/Ag in the dark and under irradiation was measured by KPFM, as shown in Figure 6j–l. The surface potential of the test area decreased from 148.9 to 122.1 mV under irradiation.…”

Phase Engineering of 2D Materials

“…In this Review, we have mostly focused on atomically sharp and clear phase boundaries. While the atomic-scale nature of phase boundaries could be investigated by TEM, − optoelectronic and electronic device properties modified by the phase engineered areas could not be properly studied by such microscopy.…”

“…To overcome the limit, complementary tools such as STM and tunneling spectroscopy that enable the investigation of local electronic structures have been adopted. ,, However, the experimental conditions for the delicate tools and a wide range of spatial dimensions of phase boundaries still require more systematic studies for rigorous characterizations of phase engineering of 2D materials. Recently, Kelvin probe force microscopy (KPFM) , and piezoelectric force microscopy (PFM) are considered promising for larger-scale phase boundary studies, which allows fundamental studies with meaningful spatial resolution and in situ device characterizations.…”