Yu Guo

Two-dimensional (2D) ultra-wide bandgap (UWBG) semiconductors are essential for extreme-condition electronics and deep-ultraviolet (UV) optoelectronics, yet their diversity is limited. Here, have established tetrahedral [MCl ₄ ] ²⁻ clusters (M = Be, Mg, Ca, Sr, Fe, Co, Ni, Zn and Cd) as effective superatomic building blocks for designing a novel family of stable 2D MCl ₂ monolayers via a bottom-up cluster-assembly strategy. These monolayers exhibit UWBG semiconducting behavior with bandgaps ranging from 3.37 to 6.92 eV (HSE06), placing them alongside h -BN and Ga ₂ O ₃ as wide-gap materials. They show strong deep-UV optical absorption with coefficients exceeding 10 ⁵ cm ⁻¹ , reaching 10 ⁶ cm ⁻¹ for BeCl ₂ at ∼140 nm. Owing to their intrinsic non-centrosymmetric C _{4 v} structure, these monolayers simultaneously exhibit pronounced out-of-plane piezoelectricity with d ₃₁ coefficients up to 31.26 pm V ⁻¹ (CoCl ₂ )—comparable to or exceeding many known 2D piezoelectrics—and a mix of Rashba–Dresselhaus spin–orbit coupling with constants α _R–D ranging from 0.10 to 0.36 eV·Å at the Γ point, significantly larger than that of α -In ₂ Se ₃ (0.097 eV·Å). All monolayers are dynamically and thermally stable, with formation energies between −1.03 and −1.89 eV atom ⁻¹ . Our work establishes that this cluster-assembly approach successfully bypasses many core challenges of top–down fabrication (such as uncontrollable defect proliferation and the resulting performance degradation), enabling the atomically precise fabrication of low-symmetry 2D materials with tailored multifunctional properties for deep-UV optoelectronic and extreme-environment electronic applications.

Benefiting from the aurophilicity and relativistic effects of gold, gold clusters exhibit uniquely intricate atomic stacking patterns and diverse superatomic orbital configurations. Our previous studies identified a series of 14-electron magnetic superatomic clusters, X@Au ₁₂ (X = Cr, Mn, Fe, Co) and 18-electron superatomic clusters with dual closed-shell geometric and electronic configurations X@Au ₁₂ (X = Mo, W). In this work, through single-atom doping of Au ₁₂ with Group IIIA–VIA elements, we successfully constructed novel 16-electron superatomic clusters, XAu ₁₂ (X = S, Se, Te). Despite the inherently weak bonding interactions and limited charge transfer between S/Se/Te atoms and the Au ₁₂ fragment, the meteor-dart-shaped architecture, characterized by low C _s symmetry, effectively mitigates inter-fragment Pauli repulsion and induces a sizeable highest occupied molecular orbital-lowest unoccupied molecular orbital (HOMO-LUMO) gap. Subsequently, by investigating O ₂ adsorption behaviors on typical clusters with distinct superatomic properties (SnAu ₁₂ , Cr@Au ₁₂ , Mo@Au ₁₂ , Te(Se)Au ₁₂ ), we established a regulatory mechanism for modulating oxidation reactivity through superatomic electronic properties. O ₂ adsorption on clusters proceeds via electron transfer mechanisms, demonstrating that oxidative activity is governed by the HOMO level and the HOMO-LUMO gap. Within the framework of the jellium model, the theoretically predicted adsorption energy trend—SnAu ₁₂ ≈ Cr@Au ₁₂ < TeAu ₁₂ ≈ SeAu ₁₂ < Mo@Au ₁₂ —is in excellent agreement with our calculation results (−0.89 eV ≈ −0.84 eV < −0.64 eV ≈ −0.63 eV < −0.62 eV). This study provides fundamental design principles for exploring superatomic clusters featuring sub-closed-shell or even open-shell electronic configurations, while also highlighting their potential for catalytic and functional applications.

Two-dimensional (2D) layered materials lacking inversion symmetry are promising candidates for nano-electromechanical and electronic technologies. Building upon the experimentally synthesized SnP2Se6 crystal, we computationally propose a novel series of inherently asymmetric group-IV-V-VI semiconductors through elemental substitution. This series encompasses monolayers of SiP2Se6, SiAs2S6, SiAs2Se6, SiAs2Te6, GeP2S6, GeP2Se6, GeAs2S6, GeAs2Se6, GeSb2S6, SnP2S6, SnP2Se6, SnAs2S6, SnAs2Se6, SnAs2Te6 and SnSb2S6. All these structures exhibit robust energetic and dynamic stability, along with excellent resistance to oxidation when exposed to air. These monolayers have moderate bandgaps ranging from 1.04 to 2.36 eV; notably, the monolayers of SiAs2Se6, SiAs2Te6, GeP2S6, GeAs2Se6 and SnAs2Te6 are direct-bandgap semiconductors. More importantly, these group-IV-V-VI monolayers exhibit significant in-plane piezoelectricity, with coefficients (d11) as high as 22.94 pm/V. Additionally, SnP2Se6 bilayer exhibit significant out-of-plane piezoelectricity (d33) with coefficients exceeding 5 pm/V. Moreover, the coexistence of room-temperature ferroelectricity in these monolayers is unambiguously confirmed by their intrinsic spontaneous polarization and remarkably low ferroelectric switching barriers. These findings establish a new paradigm for integrating piezoelectricity and ferroelectricity with diverse 2D materials, thereby opening exciting opportunities for designing multifunctional materials and developing novel electronic devices.

A sumanene monolayer, with a Kagome-like lattice and two flat bands and two Dirac cones in the band structures, can be atomically assembled by C₂₁ clusters. In this paper, first-principles simulations indicate surface charge doping can purposely shift the Fermi level between Dirac cones and flat bands. Interestingly, Li/Na/K atoms can be well distributed in bowl-like structures, transforming the semiconducting sumanene monolayer into a semimetal by shifting the Fermi energy exactly to the Dirac cone. As a natural hosting platform, sumanene shows a high theoretical storage capacity (1115.7 mAh/g for Na/K). Additionally, the moderate adsorption and very low diffusion barrier (≤0.24 eV) imply a suitable open-circuit voltage and ultrafast charge. Besides, the naturally curved and flexural configuration of sumanene effectively releases the lattice expansion during charging and discharging. Therefore, doped sumanene is a compelling anode material for alkali-metal batteries with high capacity, ultrafast charge, and high structural stability.

An in-depth study of the substrate effect is crucial for optimizing and designing the performance of two-dimensional (2D) materials in practical applications. Fullerene monolayers (FMs), a new pure carbon system successfully prepared recently, have prompted renewed interest in the question of whether FMs might be exploited to create carbon-based functional materials with improved performance. Here, the electronic structure of a MXene-supported FM was investigated by first-principles calculations. Various band offset types, including types I, II, and III, exist in the FM/M2X heterostructures, which are determined by the energy level arrangement of individual layers. Interestingly, strain also plays an important role in the band offset of the FM/M2X heterostructures. From the selection of a specific substrate and introduction of proper strain in the substrate, the desired band structure can be obtained. Our results offer profound physical insights into the mechanism of electronic structure tuning of FM by substrates.

Manipulating the symmetry of fullerene-based low-dimensional materials is crucial to the development of electronic devices and modern nonvolatile memories. However, there have been few reports on studying the physicochemical properties of fullerene and its derivatives by controlling the symmetries. Herein, we demonstrate ferroelectricity in Sc₃N@I_h-C₈₀-Pd/Pt adducts with relatively strong spontaneous polarization. Polarization originates from subtle molecular interactions between Sc₃N@I_h-C₈₀ and Pd/Pt atoms, breaking the structural symmetry. Additionally, we investigate how a temperature-dependent polar-nonpolar phase transition affects the corresponding nonadiabatic electron-hole recombination process in the ferroelectric fullerene adduct Sc₃N@I_h-C₈₀-Pd. The results indicate that polarization has a greater impact than temperature effects, resulting in an extension of the carrier lifetime in the polar phase by over 3 times compared to that in the nonpolar phase. Our findings unveil new members of the ferroelectric fullerene family and provide guidance for improving the performance of optoelectronic materials.

C₈₀ and Sc₃N@I_h–C₈₀ can be used as building blocks to assemble stable 2D lattices. These materials possess desired physical properties, including unique electronic band structures, appreciable carrier mobility, strong optical absorption, and anisotropic optical behavior.