Publications by authors named "Yanqi Ge"

Owing to their distinctive photophysical properties resulting from their larger exciton binding energy and the influence of dielectric and quantum confinement effects, considerable research interest has been directed toward two-dimensional Ruddlesden-Popper halide perovskites (2D RP-HPs). Particularly, 2D RP-HPs exhibit exceptional multiphoton absorption (MPA) effects that reveal versatile applications. In this work, two-photon absorption (2PA) and three-photon absorption (3PA) in 2D RP-HPs, specifically (PEA)PbBr and (BA)PbBr platelets, have been demonstrated through their photoluminescence spectra under multiphoton excitation, revealing a power law relationship with excitation energy.

View Article and Find Full Text PDF

Among 2D materials (Xenes) which are at the forefront of research activities, borophene, is an exciting new entry due to its uniquely varied optical, electronic, and chemical properties in many polymorphic forms with widely varying band gaps including the lightest 2D metallic phase. In this paper, we used a simple selective chemical etching to prepare borophene with a strong near IR light-induced photothermal effect. The photothermal efficiency is similar to plasmonic Au nanoparticles, with the added benefit of borophene being degradable due to electron deficiency of boron.

View Article and Find Full Text PDF

The past decades have witnessed a rapid expansion in investigations of two-dimensional (2D) monoelemental materials (Xenes), which are promising materials in various fields, including applications in optoelectronic devices, biomedicine, catalysis, and energy storage. Apart from graphene and phosphorene, recently emerging 2D Xenes, specifically graphdiyne, borophene, arsenene, antimonene, bismuthene, and tellurene, have attracted considerable interest due to their unique optical, electrical, and catalytic properties, endowing them a broader range of intriguing applications. In this review, the structures and properties of these emerging Xenes are summarized based on theoretical and experimental results.

View Article and Find Full Text PDF

The transition metal disulfides of VB group elements have gradually come into people's field of vision owing to their two-dimensional structure and unique optical properties. Vanadium diselenide (VSe) as a kind of transition metal diselenides, is competent for the applications of nonlinear saturable absorption. The dispersion of few-layer VSeis prepared by liquid phase exfoliation method.

View Article and Find Full Text PDF

Ultrathin lamellar SnSe is highly attractive for applications in areas such as photonics, photodetectors, photovoltaic devices, and photocatalysis, owing to its suitable band gap, exceptional light absorption capabilities, and considerable carrier mobility. On the other hand, SnSe nanosheets (NSs) still face challenges of being difficult to prepare and their devices having low photoelectric conversion efficiencies. Herein, ultrathin SnSe NSs with controlled Se defects were synthesized with high yield by a facial Li intercalation-assisted liquid exfoliation method.

View Article and Find Full Text PDF

Photodynamic therapy (PDT) has been extensively investigated for decades for tumor treatment because of its non-invasiveness, spatiotemporal selectivity, lower side-effects, and immune activation ability. It can be a promising treatment modality in several medical fields, including oncology, immunology, urology, dermatology, ophthalmology, cardiology, pneumology, and dentistry. Nevertheless, the clinical application of PDT is largely restricted by the drawbacks of traditional photosensitizers, limited tissue penetrability of light, inefficient induction of tumor cell death, tumor resistance to the therapy, and the severe pain induced by the therapy.

View Article and Find Full Text PDF

Low-dimensional metal-halide perovskites have exhibited significantly superior nonlinear optical properties compared to traditional semiconductor counterparts, thanks to their peculiar physical and electronic structures. Their exceptional nonlinear optical characteristics make them excellent candidates for revolutionizing widespread applications. However, the research of nonlinear photonics based on low-dimensional metal-halide perovskites is in its infancy.

View Article and Find Full Text PDF

In this paper, 2D borophene is synthesized through a liquid-phase exfoliation. The morphology and structure of as-prepared borophene are systemically analyzed, and the Z-scan is used to measure the nonlinear optical properties. It is found that the saturable absorber (SA) properties of borophene make it serve as an excellent broadband optical switch, which is strongly used for mode-locking in near- and mid-infrared laser systems.

View Article and Find Full Text PDF

Few-layered graphdiyne (GDY) was successfully fabricated and applied as a saturable absorber to generate a watt-level ultrafast solid-state bulk laser. The maximum output power of up to 1.27 W was obtained with a pulse width of 23 ps and a repetition rate of 92.

View Article and Find Full Text PDF

Mode-locking lasers have not only produced huge economic benefits in industrial fields and scientific research, but also provided an excellent platform to study diverse soliton phenomena. However, the real-time characterization of the ultrafast soliton dynamics remains challenging for traditional electronic instruments due to their relatively low response bandwidth and slow scan rate. Consequently, it is urgent for researchers to directly observe these ultrafast evolution processes, rather than just indirectly understand them from numerical simulations or averaged measurement data.

View Article and Find Full Text PDF
Article Synopsis
  • A high-quality all-carbon nanostructure called graphdiyne (GDY) was created and tested for its ability to absorb light in the 2 μm range with a commercial mode-locked laser.
  • The GDY was utilized as an optical switcher in a Q-switched Ho laser, achieving a maximum output power of 443 mW and a pulse width of 1.38 µs at a repetition rate of 29.72 kHz under 2.4 W pump power.
  • These findings indicate that GDY is a promising material for short pulse generation in Ho-doped lasers at 2.1 μm.
View Article and Find Full Text PDF
Article Synopsis
  • Black arsenic phosphorus (b-AsP) is a novel 2D material that combines properties of black phosphorus and graphene, making it appealing for photonics and photoelectronics due to its high carrier mobility and tunable band gap.
  • Researchers fabricated ultrathin b-AsP nanomaterials using liquid-phase exfoliation and characterized their optical properties, revealing strong linear and nonlinear absorptions with notable coefficients.
  • The study demonstrated that b-AsP can effectively serve as a saturable absorber in fiber lasers, producing stable laser pulses with enhanced stability against self-splitting, showcasing its potential for ultrafast photonics applications.
View Article and Find Full Text PDF

Optical nonlinearity in 2D materials excited by spatial Gaussian laser beam is a novel and peculiar optical phenomenon, which exhibits many novel and interesting applications in optical nonlinear devices. Passive photonic devices, such as optical switches, optical logical gates, photonic diodes, and optical modulators, are the key compositions in the future all-optical signal-processing technologies. Passive photonic devices using 2D materials to achieve the device functionality have attracted widespread concern in the past decade.

View Article and Find Full Text PDF

Optical techniques using developed laser and optical devices have made a profound impact on modern medicine, with "biomedical optics" becoming an emerging field. Sophisticated technologies have been developed in cancer nanomedicine, such as photothermal therapy and photodynamic therapy, among others. However, single-mode phototherapy cannot completely treat persistent tumors, with the challenges of relapse or metastasis remaining; therefore, combinatorial strategies are being developed.

View Article and Find Full Text PDF

Two-dimensional (2D) metal-free sheets with atomic thickness have been highly considered as promising candidates for fluorescent probes, due to their intriguing characteristics. In this work, 2D ultrathin boron nanosheets (B NSs) with a surface defect nanolayer can be effectively prepared by modified liquid phase exfoliation. The as-prepared ultrathin B NSs show blue fluorescence characteristics even with a quantum yield efficiency of up to 10.

View Article and Find Full Text PDF

Over the past decade, two-dimensional (2D) transition metal dichalcogenides (TMDCs) have attracted tremendous research interest for future electronics owing to their atomically thin thickness, compelling properties and various potential applications. However, interface engineering including contact optimization and channel modulations for 2D TMDCs represents fundamental challenges in ultimate performance of ultrathin electronics. This article provides a comprehensive overview of the basic understanding of contacts and channel engineering of 2D TMDCs and emerging electronics benefiting from these varying approaches.

View Article and Find Full Text PDF

Black phosphorus (BP), a prosperous two-dimensional optoelectronic material, has been deeply developed for various optoelectronics applications. Here, we demonstrate a sub-hundred nanosecond passively Q-switched Er-doped all-fiber laser with BP as the saturable absorber (SA). The BP-SA is fabricated by a controllable optical deposition technique.

View Article and Find Full Text PDF

Mixed-dimensional binary heterostructures, especially 0D/2D heterostructures, have attracted significant attention due to their unique physical properties. In this contribution, 0D bismuth quantum dots (Bi QDs, VA) are immobilized onto 2D Te nanosheets (Te NSs, VIA) to prepare Bi QDs/Te NSs binary heterostructures (Bi/Te) through a facile and cost-effective hydrothermal method. The results from both experiments and density functional theory (DFT) calculations demonstrate the enhanced photo-response behaviors of Bi/Te-based photoelectrochemical (PEC)-type photodetectors (PDs).

View Article and Find Full Text PDF

Owing to their intriguing characteristics, the ongoing pursuit of emerging mono-elemental two-dimensional (2D) nanosheets beyond graphene is an exciting research area for next-generation applications. Herein, we demonstrate that highly crystalline 2D boron (B) nanosheets can be efficiently synthesized by employing a modified liquid phase exfoliation method. Moreover, carrier dynamics has been systematically investigated by using femtosecond time-resolved transient absorption spectroscopy, demonstrating an ultrafast recovery speed during carrier transfer.

View Article and Find Full Text PDF

It is widely known that the excellent intrinsic electronic and optoelectronic advantages of bismuthene and tellurene make them attractive for applications in transistors and logic and optoelectronic devices. However, their poor optoelectronic performances, such as photocurrent density and photoresponsivity, under ambient conditions severely hinder their practical application. To satisfy the demand of high-performance optoelectronic devices and topological insulators, bismuth telluride nanoplates (BiTe NPs) with different sizes, successfully synthesized by a solvothermal approach have been, for the first time, employed to fabricate a working electrode for photoelectrochemical (PEC)-type photodetection.

View Article and Find Full Text PDF

A phototransistor based on a hybrid of graphene and BP nanosheets with a facile fabrication method and remarkable performance is presented. Unlike previously reported single BP flake-based devices, this phototransistor employs diverse BP nanosheets with different sizes and layer numbers. The wet transfer process of graphene is exploited to integrate the liquid-exfoliated BP nanosheets into the device smoothly.

View Article and Find Full Text PDF

Bismuthene, as a new two-dimensional material made up of diazo metal elements, has drawn massive attention for its unique electronic, mechanical, quantum, and nonlinear optical properties. In recent years, researchers have increasingly turned their attention to the ultrafast photonics fields based on bismuthene. However, the internal ultrashort pulse dynamics has seldom been explored yet.

View Article and Find Full Text PDF

Zero-dimensional (0D)-2D nanostructures, which combine the efficient light-harvesting properties of 0D nanocrystals (NCs) and the ultrafast carrier transfer of 2D materials, have been widely used in optoelectronic devices. Although the most common way to fabricate 0D-2D nanostructures consists of a mixing process, the limited loading efficiency of NCs and the poor 0D-2D interface hinder the efficient photo-carrier generation and fast carrier separation/transfer in such systems. Herein, the in situ synthesis of CsPbBr3/BP heterostructures via a hot-injection method was presented, revealing that both the formation process of CsPbBr3 NCs and the CsPbBr3/black phosphorous (BP) interfaces presented pronounced changes.

View Article and Find Full Text PDF

2D phosphorene, arsenene, antimonene, and bismuthene, as a fast-growing family of 2D monoelemental materials, have attracted enormous interest in the scientific community owing to their intriguing structures and extraordinary electronic properties. Tuning the monoelemental crystals into bielemental ones between group-VA elements is able to preserve their advantages of unique structures, modulate their properties, and further expand their multifunctional applications. Herein, a review of the historical work is provided for both theoretical predictions and experimental advances of 2D V-V binary materials.

View Article and Find Full Text PDF

Ultrafast photonics based on two-dimensional (2D) materials has been used to investigate light-matter interactions and laser generation, as well as light propagation, modulation, and detection. Here, 2D metal-phosphorus trichalcogenides, which are known for applications in catalysis and electrochemical storage, also exhibit advantageous photonic properties as nanoflakes that are only a few layers thick. By using an open-aperture Z-scan system, few-layer NiPS3 nanoflakes exhibited a large modulation depth of 56% and a low saturable intensity of 16 GW cm-2 at 800 nm.

View Article and Find Full Text PDF