Controlled Synthesis of Ultrathin Sb2Se3 Nanowires and Application for Flexible Photodetectors

Substrate Morphology Directs (001) Sb2Se3 Thin Film Growth by Crystallographic Orientation Filtering

Antimony chalcogenide, Sb2X3 (X = S, Se), applications greatly benefit from efficient charge transport along covalently bonded (001) oriented (Sb4X6)n ribbons, making thin film orientation control highly desirable - although particularly hard to achieve experimentally. Here, it is shown for the first time that substrate nanostructure plays a key role in driving the growth of (001) oriented antimony chalcogenide thin films. Vapor Transport Deposition of Sb2Se3 thin films is conducted on ZnO substrates whose morphology is tuned between highly nanostructured and flat. The extent of Sb2Se3 (001) orientation is directly correlated to the degree of substrate nanostructure. These data showcase that nanostructuring a substrate is an effective tool to control the orientation and morphology of Sb2Se3 films. The optimized samples demonstrate high (001) crystallographic orientation. A growth mechanism for these films is proposed, wherein the substrate physically restricts the development of undesirable crystallographic orientations. It is shown that the surface chemistry of the nanostructured substrates can be altered and still drive the growth of (001) Sb2Se3 thin films - not limiting this phenomenon to a particular substrate type. Insights from this work are expected to guide the rational design of Sb2X3 thin film devices and other low-dimensional crystal-structured materials wherein performance is intrinsically linked to morphology and orientation.

Ultrathin, High-Aspect-Ratio Bismuth Sulfohalide Nanowire Bundles for Solution-Processed Flexible Photodetectors

In this study, a novel synthesis of ultrathin, highly uniform colloidal bismuth sulfohalide (BiSX where X = Cl, Br, I) nanowires (NWs) and NW bundles (NBs) for room-temperature and solution-processed flexible photodetectors are presented. High-aspect-ratio bismuth sulfobromide (BiSBr) NWs are synthesized via a heat-up method using bismuth bromide and elemental S as precursors and 1-dodecanethiol as a solvent. Bundling of the BiSBr NWs occurs upon the addition of 1-octadecene as a co-solvent. The morphologies of the BiSBr NBs are easily tailored from sheaf-like structures to spherulite nanostructures by changing the solvent ratio. The optical bandgaps are modulated from 1.91 (BiSCl) and 1.88 eV (BiSBr) to 1.53 eV (BiSI) by changing the halide compositions. The optical bandgap of the ultrathin BiSBr NWs and NBs exhibits blueshift, whose origin is investigated through density functional theory-based first-principles calculations. Visible-light photodetectors are fabricated using BiSBr NWs and NBs via solution-based deposition followed by solid-state ligand exchanges. High photo-responsivities and external quantum efficiencies (EQE) are obtained for BiSBr NW and NB films even under strain, which offer a unique opportunity for the application of the novel BiSX NWs and NBs in flexible and environmentally friendly optoelectronic devices.

Recent Advances in Antimony Selenide Photodetectors

Photodetectors (PDs) rapidly capture optical signals and convert them into electrical signals, making them indispensable in a variety of applications including imaging, optical communication, remote sensing, and biological detection. Recently, antimony selenide (Sb2Se3) has achieved remarkable progress due to its earth-abundant, low toxicity, low price, suitable bandgap width, high absorption coefficient, and unique structural characteristics. Sb2Se3 has been extensively studied in solar cells, but there's a lack of timely updates in the field of PDs. A literature review based on Sb2Se3 PDs is urgently warranted. This review aims to provide a concise understanding of the latest progress in Sb2Se3 PDs, with a focus on the basic characteristics and the performance optimization for Sb2Se3 photoconductive-type and photodiode-type detectors, including nanostructure regulation, process optimization, and stability improvement of flexible devices. Furthermore, the application progresses of Sb2Se3 PDs in heart rate monitoring, and monolithic-integrated matrix images are introduced. Finally, this review presents various strategies with potential and feasibility to address challenges for the rapid development and commercial application of Sb2Se3 PDs.

Flexible and Stretchable Light-Emitting Diodes and Photodetectors for Human-Centric Optoelectronics

Optoelectronic devices with unconventional form factors, such as flexible and stretchable light-emitting or photoresponsive devices, are core elements for the next-generation human-centric optoelectronics. For instance, these deformable devices can be utilized as closely fitted wearable sensors to acquire precise biosignals that are subsequently uploaded to the cloud for immediate examination and diagnosis, and also can be used for vision systems for human-interactive robotics. Their inception was propelled by breakthroughs in novel optoelectronic material technologies and device blueprinting methodologies, endowing flexibility and mechanical resilience to conventional rigid optoelectronic devices. This paper reviews the advancements in such soft optoelectronic device technologies, honing in on various materials, manufacturing techniques, and device design strategies. We will first highlight the general approaches for flexible and stretchable device fabrication, including the appropriate material selection for the substrate, electrodes, and insulation layers. We will then focus on the materials for flexible and stretchable light-emitting diodes, their device integration strategies, and representative application examples. Next, we will move on to the materials for flexible and stretchable photodetectors, highlighting the state-of-the-art materials and device fabrication methods, followed by their representative application examples. At the end, a brief summary will be given, and the potential challenges for further development of functional devices will be discussed as a conclusion.

High-performance visible-near-infrared photodetector based on the N2200/Sb2Se3 nanorod arrays organic-inorganic hybrid heterostructure

Antimony selenide (Sb2Se3) is a suitable candidate for a broadband photodetector owing to its remarkable optoelectronic properties. Achieving a high-performance self-powered photodetector through a desirable heterojunction still needs more efforts to explore. In this work, we demonstrate a broadband photodetector based on the hybrid heterostructure of Sb2Se3 nanorod arrays (NRAs) absorber and polymer acceptor (P(NDI2OD-T2), N2200). Owing to the well-matched energy levels between N2200 and Sb2Se3, the recombination of photogenerated electrons and holes in N2200/Sb2Se3 hybrid heterostructure is greatly inhibited. The photodetector can detect the wavelength from 405 to 980 nm, and exhibit high responsivity of 0.39 A/W and specific detectivity of 1.84 × 1011 Jones at 780 nm without bias voltage. Meanwhile, ultrafast response rise time (0.25 ms) and fall time (0.35 ms) are obtained. Moreover, the time-dependent photocurrent of this heterostructure-based photodetector keeps almost the same value after the storge for 40 days, indicating the excellent stability and reproducibility. These results demonstrate the potential application of a N2200/Sb2Se3 NRAs heterojunction in visible-near-infrared photodetectors.

Superior Performances of Self-Driven Near-Infrared Photodetectors Based on the SnTe:Si/Si Heterostructure Boosted by Bulk Photovoltaic Effect

The upsurge of new materials that can be used for near-infrared (NIR) photodetectors operated without cooling is crucial. As a novel material with a small bandgap of ≈0.28 eV, the topological crystalline insulator SnTe has attracted considerable attention. Herein, this work demonstrates self-driven NIR photodetectors based on SnTe/Si and SnTe:Si/Si heterostructures. The SnTe/Si heterostructure has a high detectivity D* of 3.3 × 10¹² Jones. By Si doping, the SnTe:Si/Si heterostructure reduces the dark current density and increases the photocurrent by ≈1 order of magnitude simultaneously, which improves the detectivity D* by ≈2 orders of magnitude up to 1.59 × 10¹⁴ Jones. Further theoretical analysis indicates that the improved device performance may be ascribed to the bulk photovoltaic effect (BPVE), in which doped Si atoms break the inversion symmetry and thus enable the generation of additional photocurrents beyond the heterostructure. In addition, the external quantum efficiency (EQE) measured at room temperature at 850 nm increases by a factor of 7.5 times, from 38.5% to 289%. A high responsivity of 1979 mA W^-1 without bias and fast rising time of 8 µs are also observed. The significantly improved photodetection achieved by the Si doping is of great interest and may provide a novel strategy for superior photodetectors.

Embedded Integration of Sb2Se3 Film by Low-Temperature Plasma-Assisted Chemical Vapor Reaction with Polycrystalline Si Transistor for High-Performance Flexible Visible-to-Near-Infrared Photodetector

Flexible optoelectronics have garnered considerable interest for applications such as optical communication, motion capture, biosignal detection, and night vision. Transition-metal dichalcogenides are widely used as flexible photodetectors owing to their outstanding electrical and optical properties and high flexibility. Herein, a two-dimensional (2D) Sb₂Se₃ film-based one transistor-one resistor (1T1R) flexible photodetector with high photosensing current and detection ranges from visible to near-infrared was developed. The flexible 1T1R was fabricated using an efficient field-effect transistor platform with the 2D Sb₂Se₃ film directly deposited on the sensing region using a low-temperature plasma-assisted chemical vapor reaction. The photodetector could achieve a maximum I_photo/I_dark of 15,000 under white light with a power density of 26 mW/cm², in which the photodetector showed quick rising and falling response times of 0.16 and 0.28 s, respectively. The 2D Sb₂Se₃ film exhibits broadband absorption in the visible and IR regions, yielding an excellent photoresponse under laser illumination with different wavelengths. To investigate the flexibility and stability of the 1T1R photodetector, the photoresponses were measured under different bending cycles and curvatures, which maintained its functions and exhibited high stability under convex and concave bending at a curvature radius of 20 mm.

One dimensional MOSFETs for sub-5 nm high-performance applications: a case of Sb2Se3 nanowires

Low-dimensional materials have been proposed as alternatives to silicon-based field-effect transistor (FET) channel materials in order to overcome the scaling limitation. In the present research, gate-all-around (GAA) Sb₂Se₃ nanowire FETs were simulated using the ab initio quantum transport method. The gate-length (L_g, L_g = 5 nm) GAA Sb₂Se₃ FETs with an underlap (UL, UL = 2, 3 nm) could satisfy the on-state current (I_on) and delay time (τ) of the 2028 requirements for high performance (HP) applications of the International Technology Roadmap for Semiconductors (ITRS) 2013. It is interesting that the L_g = 3 nm GAA Sb₂Se₃ FETs with a UL = 3 nm can meet the I_on, power dissipation (PDP), and τ of the 2028 requirements of ITRS 2013 for HP applications. Therefore, GAA Sb₂Se₃ FETs can be a potential candidate scaling Moore's law downward to 3 nm.

Stability & durability of self-driven photo-detective parameters based on Sn1-β Sb β Se (β = 0, 0.05, 0.10, 0.15, 0.20) ternary alloy single crystals

In the present investigation Sn1-β Sb β Se crystals are grown using the direct vapor transport method. The crystals after growth were analyzed by EDAX and XPS to confirm the elemental composition. The surface morphological properties were studied by scanning electron microscope, confirming a flat surface and layered growth of the Sn1-β Sb β Se crystals. The structural properties studied by X-ray diffraction and high-resolution transmission electron microscopy confirm the orthorhombic structure of the grown Sn1-β Sb β Se crystals. The Raman spectroscopic measurements evince the presence of B2g and Ag vibration modes. The PL intensity peak at ∼400 nm to 500 nm confirms the energy band gap. The indirect energy band gap of 1.18 eV was evaluated using Tauc plot by employing UV-visible spectroscopy making it a promising candidate for optoelectronic and photonic applications. The pulse photo response of pure and doped samples was studied under a monochromatic source of wavelength 670 nm and intensity of 30 mW cm-2 at zero biasing voltage firstly on day one and then the same samples were preserved for 50 days and the stability of the photodetectors was observed. Photodetector parameters such as rise time, decay time, photocurrent, responsivity, sensitivity, and detectivity were observed, and evaluated results are presented in this article.

Sb2S3/Sb2Se3 heterojunction for high-performance photodetection and hydrogen production

Photoelectrochemical (PEC)-type devices provide promising ways for harvesting solar energy and converting it to electric and chemical energy with a low-cost and simple manufacturing process. However, the high light absorption, fast carrier separation, and low carrier recombination are still great challenges in reaching high performance for PEC devices. As emergent two-dimensional (2D) materials, Sb₂Se₃ and Sb₂S₃ exhibit desirable photoelectric properties due to the narrow bandgap, large optical absorption, and high carrier mobility. Herein, Sb₂S₃/Sb₂Se₃ heterojunction is synthesized by a two-step physical vapor deposition method. The type-II Sb₂S₃/Sb₂Se₃ heterojunction displays excellentphotoelectric properties such as a high photocurrent density (I_ph ∼ 162 µA cm^-2), a high photoresponsivity (R_ph ∼ 3700 µA W^-1), and a fast time response speed (rising time ∼ 2 ms and falling time ∼ 4.5 ms) even in harsh environment (H₂SO₄ electrolyte). Especially, the Sb₂S₃/Sb₂Se₃ shows an excellent self-powered photoresponse (I_ph ∼ 40 µA cm^-2, R_ph ∼ 850 µA W^-1). This increment is attributed to the improvement in light absorption, charge separation, and charge transfer efficiency. Taking these advantages, the Sb₂S₃/Sb₂Se₃ heterojunction also exhibits higher PEC water splitting synergically, which is approximately 3 times larger than that of Sb₂Se₃ and Sb₂S₃. These results pave the way for high-performance PEC devices by integrating 2D narrow bandgap semiconductors.

Underwater Multispectral Computational Imaging Based on a Broadband Water-Resistant Sb2Se3 Heterojunction Photodetector

Exploration, utilization, and protection of marine resources are of great significance to the survival and development of mankind. However, currently classical optical cameras suffer information loss, low contrast, and color distortion due to the absorption and scattering nature for the underwater environment. Here, we demonstrate an underwater multispectral computational imaging system combined with single-photodetector imaging algorithm technology and a CdS/Sb₂Se₃ heterojunction photodetector. The computational imaging technology coupled with an advanced Fourier algorithm can capture a scene by a single photodetector without spatial resolution that avoids the need to rely on high-density detectors array and bulky optical components in traditional imaging systems. This convenient computational imaging method provides more flexible possibilities for underwater imaging and promises to give more imaging capabilities (such as multispectral imaging, antiscattering imaging capability) to meet ever-changing demand of underwater imaging. In addition, the water-resistant CdS/Sb₂Se₃ heterojunction photodetector fabricated by the close spaced sublimation (Sb₂Se₃) and chemical bath deposition (CdS) shows excellent self-powered photodetection performance at zero bias with high LDR of 128 dB, broadband response spectrum range of 300-1050 nm, high responsivity up to 0.47 A/W, and high specific detectivity over 5 × 10¹² jones. Compared with the traditional optical imaging system, our designed computational imaging system that combines the advanced Fourier algorithm and a high-performance CdS/Sb₂Se₃ heterojunction photodetector exhibits outstanding antiscattering imaging capability (shielded by frosted glass), weak light imaging capability (∼0.2 μW/cm², corresponding to moonlight intensity), and multispectral imaging capability. Therefore, we believe that this work will boost the progress of marine science.

High-responsivity, self-driven visible-near infrared Sb2Se3 nanorod array photodetector

Anisotropic antimony selenide (Sb₂Se₃) semiconductor has received considerable attention due to its unique one-dimensional crystal structure and corresponding superior and anisotropic optical and electronic properties. It is a promising material for a wide range of applications related to electronics and optoelectronics. Herein, we demonstrate a high-performance and self-powered Sb₂Se₃ nanorod array-based core/shell heterojunction detector fabricated on glass substate. The detector shows a wide spectral photoresponse range from visible to near-infrared (405-980 nm). The detector yields a detectivity of as high as 2.06×10¹² Jones in the visible light (638 nm) and that of 1.82×10¹² Jones (830 nm) at zero bias. Due to the strong built-in filed and excellent carrier transport, the detector exhibits ultrafast response speed at both rise (30 μs) and decay (68 μs) processes. Further analysis demonstrates that the noise is mainly generated from the 1/f noise in the low frequency range, while it is affected by the shot noise and generation-recombination noise in high frequency.

Rapid, facile synthesis of InSb twinning superlattice nanowires with a high-frequency photoconductivity response

We present a self-seeded (with indium droplets) solution-liquid-solid (SLS) synthesis route for InSb nanowires (NWs) using commercially available precursors at a relatively low temperature of about 175 °C, which takes only 1 min upon the injection of reductant. Structural characterization reveals that the InSb nanowires are high quality and have twinning superlattice structures with periodically spaced twin planes along the growth direction of 〈111〉. Notably, we have measured an ultrafast conductivity lifetime in the NWs of just 9.1 ps utilizing time-resolved optical pump-terahertz probe (OPTP) spectroscopy, which may facilitate the development of high-frequency nanoscale integrated optoelectronic systems related to twinning superlattice structures.

Solution-Processed Sb2Se3 on TiO2 Thin Films Toward Oxidation- and Moisture-Resistant, Self-Powered Photodetectors

Semiconductor-sensitized TiO₂ thin films with long-term air stability are attractive for optoelectronic devices and applications. Herein, we demonstrate the potential of the TiO₂ thin film (∼800 nm in thickness) sensitized with a Sb₂Se₃ layer (∼350 nm) grown from solution spin coating and processed by annealing recrystallization at 300 °C for high-performance optical detection. The type-II band alignment, p-Sb₂Se₃/n-TiO₂ heterojunction, and narrow band gap of Sb₂Se₃ (∼1.25 eV) endow the film photodetector with a large photocurrent, high switching stability and on/off ratio (>10³), and fast response speeds (<20 ms) under the broadband visible-near-infrared irradiation in a zero-bias self-powered photovoltaic mode. In particular, the photodetector shows notable resistance to oxidation and moisture for long-term operation, which is linked to the modest surface oxidation (Sb-O) of Sb₂Se₃, as verified by X-ray photoelectron spectroscopy. The first-principles calculations show that a low and medium concentration of oxygen substitution for Se (O_Se) and oxygen interstitial (O_i) with negative formation energies can lead to such a moderate surface oxidation but do not generate impurity states or just introduce a shallow-level acceptor state in the electronic structures of Sb₂Se₃ without degrading its optoelectronic performance. Our theoretical results offer a rational explanation for the air-stable and oxidation/moisture-resistant characteristics in moderately oxidized Sb₂Se₃ and may shed light on the surface oxidation-property relationship studies of other nonoxide semiconductor-sensitized devices.

High-Crystallinity Epitaxial Sb2Se3 Thin Films on Mica for Flexible Near-Infrared Photodetectors

The V-VI binary chalcogenide, Sb₂Se₃, has attracted considerable attention for its applications in thin film optoelectronic devices because of its unique 1D structure and remarkable optoelectronic properties. Herein, we report an Sb₂Se₃ thin film epitaxially grown on a flexible mica substrate through a relatively weak (van der Waals) interaction by vapor transport deposition. The epitaxial Sb₂Se₃ thin films exhibit a single (120) out-of-plane orientation and a 0.25° full width at half-maximum of (120) rocking curve in X-ray diffraction, confirming the high crystallinity of the epitaxial films. The Sb₂Se₃(120) plane is epitaxially aligned on mica(001) surface with the in-plane relationship of Sb₂Se₃[2̅10]//mica[010] and Sb₂Se₃[001]//mica[100]. Compared to the photodetector made of a nonepitaxial Sb₂Se₃ film, the photocurrent of the epitaxial Sb₂Se₃ film photodetector is almost doubled. Furthermore, because of the flexibility and high sensitivity of the epitaxial Sb₂Se₃ film photodetector on mica, it has been successfully employed to detect the heart rate of a person. These encouraging results will facilitate the development of epitaxial Sb₂Se₃ film-based devices and potential applications in wearable electronics.

The High Anisotropy of the Epitaxial Growth of the Well-Aligned Sb2Se3 Nanoribbons on Mica

One-dimensional semiconductor nanostructures, which are different from those of bulk materials, have attracted considerable interest in either scientific research or practical application. Herein, the Sb₂Se₃ nanoribbons have been successfully synthesized by the epitaxial growth process on mica using the rapid physical vapor deposition method. The density of the Sb₂Se₃ nanoribbons increased quickly when the temperature decreased, and finally, the nanoribbons connected to each other and formed a network structure even in film. These nanoribbons were all well aligned along the preferred direction that either is parallel to each other or forms 60° angles. Further structural investigation demonstrated that the Sb₂Se₃ nanoribbons grew along the [001] directions, which are aligned along the directions [11̅0] and [100] or [100] and [110] on the mica surface. Then, an asymmetric lattice mismatch growth mechanism causing incommensurate heteroepitaxial lattice match between the Sb₂Se₃ and mica crystal structure was suggested. Furthermore, a polarized photodetector based on the film with the well-aligned Sb₂Se₃ nanoribbons was constructed, which illustrated strong photosensitivity and high anisotropic in-plane transport either in the dark or under light. The incommensurate heteroepitaxial growth method shown here may provide access to realize well-ordered nanostructures of other inorganic materials and promote the anisotropic photodetector industrialization.

Symmetry-Reduction Enhanced Polarization-Sensitive Photodetection in Core-Shell SbI3 /Sb2 O3 van der Waals Heterostructure

Structural symmetry is a simple way to quantify the anisotropic properties of materials toward unique device applications including anisotropic transportation and polarization-sensitive photodetection. The enhancement of anisotropy can be achieved by artificial symmetry-reduction design. A core-shell SbI₃ /Sb₂ O₃ nanowire, a heterostructure bonded by van der Waals forces, is introduced as an example of enhancing the performance of polarization-sensitive photodetectors via symmetry reduction. The structural, vibrational, and optical anisotropies of such core-shell nanostructures are systematically investigated. It is found that the anisotropic absorbance of a core-shell nanowire is obviously higher than that of two single compounds from both theoretical and experimental investigations. Anisotropic photocurrents of the polarization-sensitive photodetectors based on these core-shell SbI₃ /Sb₂ O₃ van der Waals nanowires are measured ranging from ultraviolet (UV) to visible light (360-532 nm). Compared with other van der Waals 1D materials, low anisotropy ratio (I_max /I_min ) is measured based on SbI₃ but a device based on this core-shell nanowire possesses a relatively high anisotropy ratio of ≈3.14 under 450 nm polarized light. This work shows that the low-symmetrical core-shell van der Waals heterostructure has large potential to be applied in wide range polarization-sensitive photodetectors.

Diverse electronic properties of 2D layered Se-containing materials composed of quasi-1D atomic chains

The two-dimensional (2D) atomically thin layered materials have attracted significant attention for constructing next-generation integrated electronic and optoelectronic devices. A special class of 2D materials composed of quasi one-dimensional (1D) atomic chains that show intriguing properties are less studied. Here, two Se-containing 2D layered materials α-Se and Sb₂Se₃ that have quasi-1D atomic chains are investigated via first-principles electronic structure calculations. Results shows that the electronic properties of n-monolayers (n-MLs) stacked α-Se and Sb₂Se₃ exhibit distinct layer-dependence electronic properties. The band gap of 2D α-Se remarkably decreases with increasing thickness, whereas the band gap of 2D Sb₂Se₃ show negligible change with thickness. The evolution of lattice phonon frequencies with thickness also show similar distinction. The underpinnings of the diverse electronic properties are attributed to the different electronic coupling among the layers of α-Se and Sb₂Se₃ that results in different van der Waals interactions among chains/layers. Our study demonstrates the rich diversity in the properties of 2D layered materials composed of lower-dimensional structural motifs.

Selenium and sulfur inhomogeneity in free-standing ternary Sb2(Se,S)3 alloyed nanorods

Chalcogen inhomogeneous distributions, i.e., S decreases but Se increases from the center to the periphery, are found in ternary Sb₂(Se,S)₃ alloyed nanorods synthesized with SeS₂ as a molecular precursor.

Solution-synthesis of Sb2Se3 nanorods using KSeCN as a molecular selenium source

Potassium selenocyanate (KSeCN) is used as a molecular selenium source to prepare Sb₂Se₃ nanorods, in which selenocyanate (SeCN⁻) anions are thermally decomposed to elemental Se(0) and then reduced to Se²⁻ anions in the organic amine medium.

Construction of 2D Antimony(III) Selenide Nanosheets for Highly Efficient Photonic Cancer Theranostics

Photonic cancer hyperthermia has been considered to be one of the most representative noninvasive cancer treatments with high therapeutic efficiency and biosafety. However, it still remains a crucial challenge to develop efficient photothermal nanoagents with satisfactory photothermal performance and biocompatibility, among which two-dimensional (2D) ultrathin nanosheets have recently been regarded as the promising multifunctional theranostic agents for photothermal tumor ablation. In this work, we report, for the first time, on the construction of a novel kind of photothermal agents based on the intriguing 2D antimony(III) selenide (Sb₂Se₃) nanosheets for highly efficient photoacoustic imaging-guided photonic cancer hyperthermia by near-infrared (NIR) laser activation. These Sb₂Se₃ nanosheets were easily fabricated by a novel but efficiently combined liquid nitrogen pretreatment and freezing-thawing approach, which were featured with high photothermal-conversion capability (extinction coefficient: 33.2 L g^-1 cm^-1; photothermal-conversion efficiency: 30.78%). The further surface engineering of these Sb₂Se₃ ultrathin nanosheets with poly(vinyl pyrrolidone) (PVP) substantially improved the biocompatibility of the nanosheets and their stability in physiological environments, guaranteeing the feasibility in photonic antitumor applications. Importantly, 2D Sb₂Se₃-PVP nanosheets have been certificated to efficiently eradicate the tumors by NIR-triggered photonic tumor hyperthermia. Especially, the biosafety in vitro and in vivo of these Sb₂Se₃ ultrathin nanosheets has been evaluated and demonstrated. This work meaningfully expands the biomedical applications of 2D bionanoplatforms with a planar topology through probing into new members (Sb₂Se₃ in this work) of 2D biomaterials with unique intrinsic physiochemical property and biological effect.

Chemical Vapor Deposition Growth of High Crystallinity Sb2 Se3 Nanowire with Strong Anisotropy for Near-Infrared Photodetectors

Low-dimensional semiconductors have attracted considerable attention due to their unique structures and remarkable properties, which makes them promising materials for a wide range of applications related to electronics and optoelectronics. Herein, the preparation of 1D Sb₂ Se₃ nanowires (NWs) with high crystal quality via chemical vapor deposition growth is reported. The obtained Sb₂ Se₃ NWs have triangular prism morphology with aspect ratio range from 2 to 200, and three primary lattice orientations can be achieved on the sixfold symmetry mica substrate. Angle-resolved polarized Raman spectroscopy measurement reveals strong anisotropic properties of the Sb₂ Se₃ NWs, which is also developed to identify its crystal orientation. Furthermore, photodetectors based on Sb₂ Se₃ NW exhibit a wide spectral photoresponse range from visible to NIR (400-900 nm). Owing to the high crystallinity of Sb₂ Se₃ NW, the photodetector acquires a photocurrent on/off ratio of about 405, a responsivity of 5100 mA W^-1 , and fast rise and fall times of about 32 and 5 ms, respectively. Additionally, owing to the anisotropic structure of Sb₂ Se₃ NW, the device exhibits polarization-dependent photoresponse. The high crystallinity and superior anisotropy of Sb₂ Se₃ NW, combined with controllable preparation endows it with great potential for constructing multifunctional optoelectronic devices.

Isovalent bismuth ion-induced growth of highly-disperse Sb2S3 nanorods and their composite with p-CuSCN for self-powered photodetectors

Trace amounts of Bi ions are able to cause the growth of highly-disperse, thin Sb₂S₃ nanorods, which exhibit potential in UV-visible self-powered photodetectors when coupled with p-CuSCN crystal clusters.

Composition-Dependent Aspect Ratio and Photoconductivity of Ternary (BixSb1-x)2S3 Nanorods

The chemical composition, size and shape, and surface engineering play key roles in the performance of electronic, optoelectronic, and energy devices. V₂VI₃ (V = Sb, Bi; VI = S, Se) group materials are actively studied in these fields. In this paper, we introduce a colloidal method to synthesize uniform ternary (Bi_xSb_1-x)₂S₃ (0 < x < 1) nanorods. These nanorods show composition-dependent aspect ratios, enabling their composition, size, and shape control by varying Bi/Sb precursor ratios. It is found that the surface passivation by various thiols (L-SH) efficiently enhances the photoconductivity and optical responsive capability of (Bi_xSb_1-x)₂S₃ nanorods when used as active materials in indium tin oxide (ITO)/(Bi_xSb_1-x)₂S₃/ITO optoelectronic devices. Meanwhile, the increase of Sb content causes a gradual deterioration of photoconductivity of thiol-passivated nanorods. We propose that the thiol passivation is able to reduce the number of S vacancies, which act as the recombination centers (trapped states) for photogenerated electrons and holes, and thus boosts the carrier transport in (Bi_xSb_1-x)₂S₃ nanorods, and in particular that the composition-related conductivity deterioration is attributed to the increase of unpassivated S vacancies and surface oxidation due to the rise of Sb content.

Flexible Photodetectors Based on Novel Functional Materials

Flexible photodetectors have attracted a great deal of research interest in recent years due to their great possibilities for application in a variety of emerging areas such as flexible, stretchable, implantable, portable, wearable and printed electronics and optoelectronics. Novel functional materials, including materials with zero-dimensional (0D) and one-dimensional (1D) inorganic nanostructures, two-dimensional (2D) layered materials, organic semiconductors and perovskite materials, exhibit appealing electrical and optoelectrical properties, as well as outstanding mechanical flexibility, and have been widely studied as building blocks in cost-effective flexible photodetection. Here, we comprehensively review the outstanding performance of flexible photodetectors made from these novel functional materials reported in recent years. The photoresponse characteristics and flexibility of the devices will be discussed systematically. Summaries and challenges are provided to guide future directions of this vital research field.

Solution processing of chalcogenide materials using thiol–amine “alkahest” solvent systems

We highlight recent studies utilizing thiol/amine mixtures to dissolve bulk inorganic materials for facile solution processing of functional thin films.

Colloidal synthesis and characterization of single-crystalline Sb2Se3 nanowires

Single-crystalline Sb₂Se₃ nanowires have been synthesized by a hot-injection phosphine-free colloidal method and show excellent photoelectrochemical properties.

An Antimony Selenide Molecular Ink for Flexible Broadband Photodetectors

The need for low-cost high-performance broadband photon detection with sensitivity in the near infrared (NIR) has driven interest in new materials that combine high absorption with traditional electronic infrastructure (CMOS) compatibility. Here, we demonstrate a facile, low-cost and scalable, catalyst-free one-step solution-processed approach to grow one-dimensional Sb₂Se₃ nanostructures directly on flexible substrates for high-performance NIR photodetectors. Structural characterization and compositional analyses reveal high-quality single-crystalline material with orthorhombic crystal structure and a near-stoichiometric Sb/Se atomic ratio. We measure a direct band gap of 1.12 eV, which is consistent with predictions from theoretical simulations, indicating strong NIR potential. The fabricated metal-semiconductor-metal photodetectors exhibit fast response (on the order of milliseconds) and high performance (responsivity ~ 0.27 A/W) as well as excellent mechanical flexibility and durability. The results demonstrate the potential of molecular-ink-based Sb₂Se₃ nanostructures for flexible electronic and broadband optoelectronic device applications.

Organometallically Anisotropic Growth of Ultralong Sb2Se3 Nanowires with Highly Enhanced Photothermal Response

Ultralong orthorhombic Sb2Se3 nanowires have been successfully fabricated via an alternative facile organometallic synthetic route from the reaction of triphenylantimony(III) with dibenzyldiselenide in oleylamine at 180-240 °C without any other additives. The formation and growth mechanism of the Sb2Se3 nanowires is intensively investigated, and it is found that the anisotropic growth of the nanowires with almost constant diameters is resulted from the synergistic effects of the intrinsic property of the orthorhombic crystal structure and the weak binding assistance of oleylamine, and the length of the nanowires can be elongated easily by increasing reaction time in the synthetic route. Moreover, the photothermal response of the Sb2Se3 nanowires is first evaluated under illumination of UV light (320-390 nm), and it is especially noted that the Sb2Se3 nanowires exhibit highly enhanced photothermal responses (more than two times the intensity) as compared to the bulk Sb2Se3. In addition, the Sb2Se3 nanowires show excellent light-to-heat performance, which is superior to that of the nanostructured titanium dioxide and silicon powder under the same conditions.

A highly sensitive flexible SnS thin film photodetector in the ultraviolet to near infrared prepared by chemical bath deposition

A novel flexible broad band UV-vis-NIR SnS photodetector with high photosensitivity and fast response time for scientific and industrial applications.