Structural Phase Transition and Bandgap Control through Mechanical Deformation in Layered Semiconductors 1T–ZrX2 (X = S, Se)

• Published in: ACS materials letters 2020-09, Vol.2 (9), p.1115-1120
• Main Authors: Martino, Edoardo, Santos-Cottin, David, Le Mardelé, Florian, Semeniuk, Konstantin, Pizzochero, Michele, Čerņevičs, Kristia̅ns, Baptiste, Benoît, Delbes, Ludovic, Klotz, Stefan, Capitani, Francesco, Berger, Helmuth, Yazyev, Oleg V, Akrap, Ana
• Format: Article
• Language: English
• Subjects: Physics
• ISSN: 2639-4979; 0002-7863; 2639-4979; 1520-5126
• DOI: 10.1021/acsmaterialslett.0c00252

Applying elastic deformation can tune a material’s physical properties locally and reversibly. Spatially modulated lattice deformation can create a bandgap gradient, favoring photogenerated charge separation and collection in optoelectronic devices. These advantages are hindered by the maximum elastic strain that a material can withstand before breaking. Nanomaterials derived by exfoliating transition metal dichalcogenides (TMDs) are an ideal playground for elastic deformation, as they can sustain large elastic strains, up to a few percent. However, exfoliable TMDs with highly strain-tunable properties have proven challenging for researchers to identify. We investigated 1T-ZrS2 and 1T-ZrSe2, exfoliable semiconductors with large bandgaps. Under compressive deformation, both TMDs dramatically change their physical properties. 1T-ZrSe2 undergoes a reversible transformation into an exotic three-dimensional lattice, with a semiconductor-to-metal transition. In ZrS2, the irreversible transformation between two different layered structures is accompanied by a sudden 14% bandgap reduction. These results establish that Zr-based TMDs are an optimal strain-tunable platform for spatially textured bandgaps, with a strong potential for novel optoelectronic devices and light harvesting.