Dec 6, 2024
11:15am - 11:30am
Hynes, Level 2, Room 200
Fengfei Zhang1,Eva Aw1,Alexander Eaton2,Oliver Payton3,Loren Picco3,Christopher Howard1,Adam Clancy1
University College London1,University of Cambridge2,Bristol Nanodynamics Ltd.3
Fengfei Zhang1,Eva Aw1,Alexander Eaton2,Oliver Payton3,Loren Picco3,Christopher Howard1,Adam Clancy1
University College London1,University of Cambridge2,Bristol Nanodynamics Ltd.3
By cutting 2D nanomaterials into 1D nanoribbons, their properties may be tuned by width-dependent quantum confinement. Phosphorene is one of the most studied 2D materials, and our group recently developed a route the bulk synthesizing its nanoribbon analogue [1], which are predicted to exhibit exotic properties, including the Seebeck effect, tunable layer-dependent electronic, optical and ionic transport properties. Recent experiments have demonstrated room-temperature magnetism [2] in PNRs and their ability to enhance hole mobility in solar cells [3]. By combining the flexibility and unidirectional properties of nanoribbons with the high surface area and anisotropic properties of 2D phosphorene sheets, PNRs are expected to exhibit high conductivity due to the 2D confinement of electronic movements and edge effects.<br/><br/>An important approach to modifying layered materials is via alloying, as is well established for transition metal dichalcogendides. This approach may be accomplished for bP via alloying phosphorus with its group 15 neighbour, arsenic (As). By partial substitution of phosphorus with arsenic precursors in typical black phosphorus (bP) syntheses, so-called black AsP (bAsP) is formed with the orthorhombic puckered honeycomb lattice structure of bP, but with a fraction of the P atoms replaced by As atoms over a continuum of As:P ratios.<br/><br/>Here, we expand nanoribbon formation to bAsP, creating the first every alloyed 1D nanoribbons. By ionically etching the layered crystal black arsenic−phosphorus using lithium electride followed by dissolution in amidic solvents, solutions of AsPNRs are formed. The ribbons are typically fewlayered,<br/>several micrometers long with widths tens of nanometers across, and both highly flexible and crystalline. The AsPNRs are highly electrically conducting above 130 K due to their small bandgap (ca. 0.035 eV) [4], paramagnetic in nature, and have high hole mobilities, as measured with the first generation of AsP devices, directly highlighting their properties and utility in electronic devices such as near-infrared detectors, quantum computing, and charge carrier layers in solar cells.<br/><br/>The AsPNRs are synthesised using a two-step method. Firstly, bAsP is intercalated with alkali metal ions, followed by exfoliation to form stable liquid dispersions of AsPNRs [5]. This scalable approach allows us to isolate high quality individual AsPNRs from bulk bAsP. By comparing different fractions of As in the initial bAsP, we can probe the mechanism of formation and tune our materials. Interestingly, the intermediate intercalation compound has been shown to be superconducting, a property we are currently investigating alongside Cambridge Cavendish Laboratory.<br/><br/>[1] Watts, M. C. <i>et al. </i>Production of phosphorene nanoribbons. <i>Nature </i><b>568</b>, 216–220 (2019).<br/>[2] Ashoka, A. <i>et al. </i>Room Temperature Optically and Magnetically Active Edges in Phosphorene Nanoribbons. <i>Under Rev. </i>(2022).<br/>[3] Macdonald, T. J. <i>et al. </i>Phosphorene Nanoribbon-Augmented Optoelectronics for Enhanced Hole Extraction. <i>J. Am. Chem. Soc </i><b>143</b>, 21549–21559 (2021).<br/>[4] Feng Fei Zhang. <i>et al</i>. Production of Magnetic Arsenic–Phosphorus Alloy Nanoribbons with Small Band Gaps and High Hole Conductivities. <i>J. Am. Chem. Soc </i><b>145</b>, 18286–18295 (2023).<br/>[5] Cullen, P. L. <i>et al. </i>Ionic solutions of two-dimensional materials. <i>Nat. Chem. </i><b>9</b>, 244–249 (2017).