Pentagonal 2D Transition Metal Dichalcogenides: PdSe₂ and Beyond

Abstract

2D materials with common hexagonal crystal structures, such as graphene, hexagonal boron nitride, and transition metal dichalcogenides have attracted great interest due to their novel physical and chemical properties. Pentagonal transition metal dichalcogenides (TMDs) exhibit distinct optical, electrical, and chemical properties, with valuable functionalities for various applications. This review highlights some of the most important developments in this field, with emphasis on their functionalities for neuromorphic computing, transistors, photodetection, catalysts, etc. Strategies for modifying their physical and chemical properties as well as device performance including defect engineering and interface engineering are presented. Finally, a forward‐looking outlook of pentagonal 2D materials is discussed.

Research Process on Photodetectors based on Group‐10 Transition Metal Dichalcogenides

“…The present family of group‐10 TMDCs is limited and restricted to several binary compounds. [ 188 ] High throughput computing (a theoretical calculation) can predict new members of group‐10 TMDCs as thousands of 2D materials exist theoretically. [ 189 ] In the future, there is the possibility to discover more members, such as semiconductors, insulators, and topological materials, that could have potential applications in multidisciplinary applications. Large‐area and high‐quality synthesis .…”

Layer-dependent electronic structures and optical properties of two-dimensional PdSSe

“…[21][22][23][24][25] Furthermore, group 10 noble metal dichalcogenides (NMDCs) have attracted increasing attention recently. [26][27][28][29][30] NMDCs not only possess anisotropic structures, low-energy differences between different crystalline phases and controllable phase transitions compared to conventional TMDCs, but also exhibit promising application potential in field-effect transistors, photodetectors, sensors, photocatalysts and photovoltaic cells. [31][32][33][34][35][36][37] Particularly, the bulk phases of diselenides or disulphides of palladium (PdX 2 , X = S, and Se) crystallize in a peculiar puckered pentagonal structure (2O type), instead of the common 1T, 2H or 3R structure of TMDCs.…”

“…[44][45][46][47][48][49][50] Owing to the low-symmetry pentagonal layer structure, PdX 2 materials show intriguing properties including layer-related band gaps, bipolar charge transport with high carrier mobility, excellent thermoelectric performances, and pressure/strain modulated superconducting and ferroelastic phenomena. 23,[26][27][28][29][30][51][52][53][54][55][56] Furthermore, the bulk phases of PdX 2 hold the Pbca space group and the D 2h (mmm) point group, while the symmetries of few-layer PdSe 2 differ from those of the bulk phase. 57 The evenlayer PdSe 2 belongs to the Pca2 1 space group and C 2v (mm2) point group without inversion symmetry, whereas the odd-layer PdSe 2 belongs to the P2 1 /c space group and C 2h (2/m) point group with inversion symmetry.…”

“…21–25 Furthermore, group 10 noble metal dichalcogenides (NMDCs) have attracted increasing attention recently. 26–30 NMDCs not only possess anisotropic structures, low-energy differences between different crystalline phases and controllable phase transitions compared to conventional TMDCs, but also exhibit promising application potential in field-effect transistors, photodetectors, sensors, photocatalysts and photovoltaic cells. 31–37…”

“…44–50 Owing to the low-symmetry pentagonal layer structure, PdX 2 materials show intriguing properties including layer-related band gaps, bipolar charge transport with high carrier mobility, excellent thermoelectric performances, and pressure/strain modulated superconducting and ferroelastic phenomena. 23,26–30,51–56…”