Engineering Bulk Photovoltaic Effect in 2D Transition Metal Dichalcogenides.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• The bulk photovoltaic effect (BPVE) offers a route to photocurrents exceeding the Shockley-Queisser limit in non-centrosymmetric materials.
• Two-dimensional transition metal dichalcogenides (2D TMDs) are ideal platforms for BPVE due to strong light-matter interactions and tunable properties.

Purpose of the Study:

• To systematically review methods for inducing and enhancing BPVE in 2D TMDs.
• To explore the impact of phase engineering and structural modifications on BPVE performance.
• To present design guidelines for optimizing BPVE in 2D TMD systems for energy harvesting.

Main Methods:

• Analysis of phase transitions (e.g., 2H → 1T/1T', 2H → 3R) that break inversion symmetry.
• Investigation of structural modifications: strain fields, van der Waals heterostructures, twisted bilayers, lattice distortions, and rolled morphologies.
• Examination of spontaneous polarization in piezoelectric and ferroelectric 2D materials.

Main Results:

• Phase transitions and structural engineering significantly modify symmetry and electronic structure, regulating BPVE.
• Piezoelectric and ferroelectric 2D materials exhibit large photocurrents driven by spontaneous polarization.
• Polarization field directionality, edge contacts, and depolarization fields critically influence photovoltaic response.

Conclusions:

• 2D TMDs offer versatile platforms for advanced BPVE engineering through controlled phase and structural modifications.
• Optimized BPVE in 2D TMDs has significant potential for next-generation energy-harvesting and optoelectronic devices.