Pressure induced metallization with absence of structural transition in layered MoSe2

TL;DR

This study demonstrates that MoSe2 undergoes pressure-induced metallization without structural transition, highlighting its potential for tunable optoelectronic applications.

Contribution

It reveals the unique pressure-driven electronic transition in MoSe2, contrasting with MoS2, and emphasizes the role of chalcogenide layers in structural stability.

Findings

MoSe2 becomes metallic under pressure without structural change.

The band-gap narrows gradually leading to metallization.

Pressure tuning affects its optoelectronic properties.

Abstract

Layered transition-metal dichalcogenides have emerged as exciting material systems with atomically thin geometries and unique electronic properties. Pressure is a powerful tool for continuously tuning their crystal and electronic structures away from the pristine states. Here, we systematically investigated the pressurized behavior of MoSe2 up to ~ 60 GPa using multiple experimental techniques and ab -initio calculations. MoSe2 evolves from an anisotropic two-dimensional layered network to a three-dimensional structure without a structural transition, which is a complete contrast to MoS2. The role of the chalcogenide anions in stabilizing different layered patterns is underscored by our layer sliding calculations. MoSe2 possesses highly tunable transport properties under pressure, determined by the gradual narrowing of its band-gap followed by metallization. The continuous tuning of its electronic structure and band-gap in the range of visible light to infrared suggest possible energy-variable optoelectronics applications in pressurized transition-metal dichalcogenides.