Yanpeng Liu

In situ electric tuning (ISET) integrated with scanning tunneling microscopy and spectroscopy (STM/STS) has established itself as a highly effective methodology for controlling quantum electronic states in low‐dimensional materials. This approach combines the sub‐atomic spatial resolution and meV‐resolved spectroscopic capability of STM with the reversible and continuously tunable carrier modulation of field‐effect device architectures. To date, this approach has been applied to numerous systems, including graphene‐based van der Waals heterostructures, correlated electron systems, and moiré superlattice systems hosting emergent quantum phases. Herein, we systematically summarize the state‐of‐the‐art experimental implementations, including global electrostatic gating, tip‐induced local gating, tip‐induced voltage pulse, and in‐plane electric tuning, accompanied with distinct physics under each configuration. We then highlight key representative advances in resolving gate‐dependent band renormalization, correlated insulating states, charge ordering, symmetry breaking, and electrically driven metastable phases at the nanoscale. We discuss practical limitations, such as restricted carrier‐density ranges, tip‐induced perturbations, dielectric reliability, and challenges in decoupling electric effects from current injection and Joule heating. Looking forward, we outline future directions in device engineering, including programmable local electrostatics, scalable architectures, and integrated platforms for operando studies, highlighting their potential to enable deterministic control of emergent quantum phases in functional materials.

Electron acceptors such as tetracyanoquinodimethane (TCNQ) and its fluorinated analogue F4TCNQ are foundational to charge-transfer and doping chemistry. At interfaces formed by deposition of these acceptors onto donor substrates, reduced anionic species can naturally coexist with unreacted neutral acceptors, creating mixed-valence environments beyond conventional one-way charge transfer. Here, we report charge-resonance polymerization of acceptors at donor–acceptor interfaces. Deposition of neutral acceptors onto electron-donor substrates partially reduces the acceptors to anion salts, establishing neutral/radical-anion contact. This mixed-valence interface enables cyclic neutral–anion charge-resonance interactions that initiate a self-propagating polymerization process. This dynamic process operates across diverse donor substrates and from room temperature to 250 °C, producing large-area membranes up to 30 × 30 cm with persistent radicals and room-temperature magnetic hysteresis. These findings establish intraspecies charge resonance as a design principle for self-activating polymerization and offer fresh insight into charge behavior at donor–acceptor interfaces.

Silicon (Si) is a promising anode material for next‐generation lithium‐ion batteries due to its ultrahigh theoretical capacity, abundance, and favorable operating potential. However, its widespread application is limited by severe volume expansion, sluggish lithium‐ion transport, and unstable solid electrolyte interphase (SEI). Inspired by the multifunctional architecture of biological cell membranes, we report a facile and scalable strategy to construct a bio‐inspired protective interface via in situ formation of a conjugated microporous thermoset (CMT) coating on Si particles. This process involves simple hand‐mixing of a molecular precursor with Si, followed by a one‐step thermosetting treatment featuring sequential sublimation, melting, debromination, and polymerization, without the need for post‐processing. The resulting CMT interface offers micropores (∼0.5 nm) for selective Li ⁺ transport while excluding electrolyte and anions, a covalently crosslinked yet resilient network to accommodate mechanical strain, and tailored interfacial chemistry that induces a LiBr‐rich SEI to enhance Li ⁺ transport kinetics. As a result, the engineered Si@CMT anode achieves a high capacity of 3130.9 mAh g ⁻¹ at 0.1 C, maintains 1811.8 mAh g ⁻¹ at 3 C, and delivers 1838.8 mAh g ⁻¹ after 250 cycles at 0.2 C. This practical and generalizable interfacial design offers a promising route toward scalable stabilization of high‐capacity anodes.

Large-area high-quality dielectrics are essential for the integration of two-dimensional (2D) transistors. However, this integration remains challenging, especially for conventional dielectrics that require deposition processes. Adopting van der Waals (vdW) dielectrics is attractive. Molybdenum trioxide (α-MoO ₃ ) has been demonstrated as a vdW dielectric in 2D field-effect transistors (FETs), but previous demonstrations showed limited performance and small size. Here, we grow large-area single-crystalline MoO ₃ with uniform thickness and explore its properties as a dielectric. Single-crystalline MoO ₃ reaches the millimeter scale and maintains a high dielectric constant of ~ 18.5, low gate leakage of approximately 10 ⁻² A cm ⁻² at 3.0 MV cm ^−1, and a large breakdown field of ~ 26.75 MV cm ⁻¹ . Top-gated molybdenum disulfide (MoS ₂ ) transistors exhibit an average subthreshold swing of ~ 71 mV dec ⁻¹ , and an on/off current ratio exceeding 10 ⁸ . Furthermore, we demonstrate MoO ₃ -based integrated circuits and low-power complementary metal-oxide-semiconductor (CMOS) inverters.

Harnessing transition metal dichalcogenides (TMDCs) for memristors provides a promising pathway toward high‐density data storage and neuromorphic functionalities. Yet the single operation mode and insufficient on/off ratio extremely restrict the ultimate device performance. Here, we design and construct a high‐order superlattice‐based memristor by rolling up oxide/TMDCs heterostructures, which exhibits tunable resistive switching polarity and a high on/off ratio. Four types of heterostructures are created via fine‐controlled oxygen plasma to in situ oxidize the top few layers into uniform transition metal oxide. Capillary forces in organic reagents are utilized to drive these heterostructures to spontaneously roll up. The as‐formed high‐order oxide/TMDCs superlattices with alternately stacked TMDCs and oxides are clearly resolved by the cross‐section scanning transmission electron microscope and corresponding elemental mappings. With pre‐set oxide layers supplying mobile oxygen atoms, bipolar resistive switching of the high‐order superlattice‐based memristors is realized in vertical tunneling current measurements. In contrast, when the top and bottom electrodes are arranged in an interleaved configuration, the spatial confinement of conductive filaments converts the switching behavior into a unipolar mode. Furthermore, this polarity‐tunable memristor exhibits an outstanding on/off ratio of approximately 10 ⁷ and a robust multilevel resistance performance. Our work opens a new avenue for the fundamental design of high‐performance and multimodal memristors.

Tellurene, covalently bonded tellurium (Te) atoms, is one of the most chemically tractable materials in the low-dimensional community. However, the monoelemental nature and structural simplicity limit synthesis-accessible tellurene merely in the β-phase, assembled by helical Te chains with a trigonal lattice. The nonplanar structure confines tellurene at the micrometer scale and poses technological challenges toward van der Waals integrations. Here, we report an ultraflat phase of tellurene, named as θ-tellurene, over the centimeter scale via a buffer-assisted epitaxial method on the Au(100) crystal. Such a tellurene phase possesses well-aligned flat-lying 1D Te chains in monatomic zigzag configuration, as verified by scanning tunneling microscopy, noncontact atomic force microscopy, scanning transmission electron microscopy, and density functional theory calculations. Ultraflat θ-tellurene evolves through extended Ostwald ripening and dissociation-triggered transformation on a Te buffer layer, initiated and controlled by postannealing treatment. θ-Tellurene exhibits an n-type semiconducting behavior with a band gap of ∼1.55 eV and exhibits 2-fold in-plane mirror symmetry.

Gold single atoms (GSAs) have attracted considerable attentions due to their potential in electrocatalytic and photocatalytic reactions. However, achieving high gold density in conventional wet‐solution or mechanical approaches remains currently challenging, apart from uncontrolled spatial on‐support distributions, undesired bi‐products and wastes. Here we show that single gold atoms can be synthesized and patterned via a top‐down intercalation method, in which the topmost layer of gold (100) crystal evolves into isolated single atoms (conversion rate up to 25%) chiseled by a phosphorus monolayer. Scanning tunneling microscopy, X‐ray photoemission spectroscopy, and density functional theory calculations reveal that GSAs assemble into well‐ordered (2 × 2) arrays without thermodynamic tendency for coalescence and weakly couple with the underlying non‐planar phosphorus layer toward efficient hydrogen evolution reaction and oxygen evolution reaction catalysis. The on‐surface formation of GSAs can be readily tailored by varying the post‐annealing temperature and durations. This protocol is defect‐free, solvent‐free, eco‐friendly, scalable, and could regenerate a batch‐to‐batch of fresh GSAs arrays via a simple sputtering and intercalation process in case of catalyst deactivation. This work opens a green and sustainable way for the facile preparation of high‐density GSAs for efficient on‐surface electro‐/photo‐catalytic applications.

Palladium phosphide sulfide (PdPS), a two-dimensional (2D) semiconductor with a unique Cairo pentagonal lattice, shows great potential for optoelectronic and thermoelectric applications. However, its electronic transport behavior is strongly influenced by intrinsic defects. In this work, we systematically investigate the formation mechanisms and electronic consequences of intrinsic point defects in few-layer PdPS using first-principles calculations. We evaluate the formation energies of sulfur (S), phosphorus (P), and palladium (Pd) vacancies, as well as the interstitial Pd atoms and reveal their impacts on the electronic band structure. Unlike common 2D semiconductors like MoS2, PdPS hosts more low-energy defect configurations, which lead to bandgap narrowing, in-gap states as well as a Fermi level shift toward the conduction band. To validate the theoretical predictions, scanning tunneling microscopy measurements were performed, revealing the distinct defect morphologies and confirming the emergence of in-gap states under controlled annealing conditions. Complementary electrical transport measurements reveal a significantly reduced Schottky barrier height and significantly improved electron transport properties, attributed to the defect-induced electronic structure modulation. These results provide atomic-scale insights into the defect-driven phenomena in 2D PdPS, offering a pathway for tailoring electronic properties via defect engineering for future field-effect transistor applications.