Applications In Multifunctional Devices Research Articles

Broad/narrowband switchable terahertz absorber based on Dirac semimetal and strontium titanate for temperature sensing.

A broadband and narrowband switchable terahertz (THz) absorber based on a bulk Dirac semimetal (BDS) and strontium titanate (STO) is proposed. Narrowband and broadband absorption can be switched by adjusting the Fermi level of the BDS. When the Fermi level of the BDS is 100meV, the device is an absorber with three narrowband absorption peaks. The frequencies are 0.44, 0.86, and 1.96THz, respectively, when the temperature of STO is 250K. By adjusting the temperature of STO from 250 to 500K, the blue shifts of the frequencies are approximately 0.14, 0.32, and 0.60THz, respectively. The sensitivities of the three absorption peaks are 0.56, 1.27, and 2.38GHz/K, respectively. When the Fermi level of the BDS is adjusted from 100 to 30meV, the device can be switched to a broadband absorber with a bandwidth of 0.70THz. By adjusting the temperature of STO from 250 to 500K, the central frequency shifts from 1.40 to 1.79THz, and the bandwidth broadens from 0.70 to 0.96THz. The sensitivity of the central frequency is 1.57GHz/K. The absorber also has a wide range of potential applications in multifunctional tunable devices, such as temperature sensors, stealth equipment, and filters.

A superhard sp2–sp3 hybridized orthorhombic carbon allotrope with conductive property under extreme pressure

Superhard materials with conductive properties are extremely important. They have potential applications in multifunctional devices under extreme natural conditions. Here we present a superhard and conductive sp2–sp3 mixed hybrid carbon allotrope through Density functional theory calculations. The proposed carbon phase contains 36 atoms in an orthorhombic unit cell with Pmmm symmetry. In present structure (namely poC36), the sp2 bonds are wrapped around inside the sp3 bonded network. At 0 GPa it is dynamically stable and energetically more favourable than fullerene C60, graphene, Orth-C10, orth-C 10′ , oC36, C48, C20-sc, C21-sc, M-carbon, W-carbon etc. At 47.2 GPa pressure it is energy becomes lower than graphite. The Vickers hardness value is 76.32 GPa, which is higher than cubic boron nitride, the second hardest material. At 0 GPa it is an indirect band gap semi-conductor with band gap 0.08 eV. At around 11 GPa pressure, the valence band crosses the conduction band generating 1D conductivity in poC36. These, interesting features make poC36 a useful material for mechanical tools and electronic devices. The Raman spectra exhibits a diamond-like band, alongside graphite-like G and D bands, all of which undergo rightward shifts with increasing pressure, indicating structural changes. X-ray diffraction at 0 GPa resembles diamond, but at 47 GPa, four peaks vanish while six new ones emerge, signifying significant structural alterations under high pressure.

Study on the piezoelectric properties and the mechanism of strain-regulated piezoelectricity in flexible Janus monolayers Cr2X3Y3 (X/Y = Cl, Br, I)

Piezoelectric materials hold significant promise in piezoelectric electronics and piezoelectric optoelectronics. As a new member of this family, the 2D Janus structures characterized by central symmetry breaking have attracted much attention due to the out-of-plane piezoelectric effects. In this work, the mechanical, piezoelectric properties, and the strain regulation mechanism of Juans structure material (Cr2X3Y3, X/Y = Cl, Br, I) are systematically investigated by the first-principles methods. The calculated mechanical properties show that Cr2X3Y3 with a lower Young’s modulus of 27.31∼29.76 N m−1 is more sensitive to applied stresses, theoretically exhibiting exceptional piezoelectric properties. The in-plane piezoelectric coefficients d 11 for Cr2Br3Cl3, Cr2I3Cl3, and Cr2I3Br3 are 4.92, 9.89, and 7.86 pm V−1, respectively; the out-of-plane piezoelectric coefficients d 31 are 1.13, 2.33, and 1.64 pm V−1, respectively. Cr2I3Cl3 has the highest values of d 11 and d 31 due to the large electronegativity difference between iodine and chlorine atoms. Based on the analysis, it can be deduced that Cr2X3Y3 demonstrates substantial piezoelectric responses in both in- and out-of-plane, with potential strain regulation effects. The d 31 values of Cr2I3Cl3 show an approximately linear relationship to strain in the range from −2% to 4% and remain consistently above 2.10 pm V−1 across a broader range of strain from −4% to 6%, underscoring its robustness to strain. Our study indicates that two-dimensional Janus Cr2X3Y3 monolayers would emerge as promising candidates for diverse applications in multifunctional electronic devices.

Prediction of the two-dimensional ferromagnetic semiconductor Janus 2H-ZrTeI monolayer with large valley and piezoelectric polarizations.

Two-dimensional room-temperature Janus ferrovalley semiconductors with valley polarization and piezoelectric polarization offer new perspectives for designing multifunctional nanodevices. Herein, using first-principles calculations, we predict that the Janus 2H-ZrTeI monolayer is an intrinsic ferromagnetic semiconductor with in-plane magnetic anisotropy and a Curie temperature of 111 K. The Janus ZrTeI monolayer possesses a significant valley polarization of 141 meV due to time-reversal and inversion symmetry breaking. Based on the valley-contrasting Berry curvature, the anomalous valley Hall effect can be observed under an in-plane electric field. Meanwhile, the breaking of the inversion symmetry and mirror symmetry results in large longitudinal and transverse piezoelectric coefficients. By applying biaxial strain, the Janus 2H-ZrTeI monolayer can also be transformed into a Weyl nodal line semimetal. Furthermore, bilayers of ZrTeI with AB and BA stacking configurations allow the coexistence of valley polarization and ferroelectricity, enabling the manipulation of magnetism, ferroelectric polarization, and valley polarization through interlayer sliding. Our work provides a platform for studying valley polarization, piezoelectricity, and multiferroic coupling, which is significant for the application of multifunctional devices.

Intercross-linked aramid nanofibers/graphene hybrid films toward high mechanical strength and electrical conductivity

Although macro graphene films exhibit excellent electrical conductivity, the low tensile strength severely hampers the application of graphene films. Combined with polymers can improve the mechanical properties to a degree, but it usually dramatically decreases the electrical conductivities of graphene films. It is thus a great challenge to make a trade-off between high electrical conductivity and excellent mechanical properties of graphene films. Herein, we designed a homogeneous layer-by-layer microstructure combining reduced graphene oxide (rGO) nanosheets with aramid nanofiber (ANF) to obtain composite films referred to as rGO/ANF. By tuning the concentration of ANF, a balanced electrical and mechanical performance can be achieved. It is revealed that the tensile strength of the optimized composite film with 10 wt% ANF was dramatically improved by 194% comparing to the pure rGO film, and the electrical conductivity still maintained at a relatively high level (8495 S m−1). The remarkable overall properties can be attributed to the unique structure with abundant hydrogen bonds and π-π interactions formed between rGO and ANF. The results demonstrate that this is indeed an efficient strategy to balance the electrical conductivity and tensile strength of the graphene-polymer composites, making it promising in the application of multi-functional electronic devices.

Nonsaturating Linear Magnetoresistance Manifesting Two-Dimensional Transport in Wet-Chemical Patternable Bi2O2Te Thin Films.

Two-dimensional (2D) materials with exotic transport behaviors have attracted extensive interest in microelectronics and condensed matter physics, while scaled-up 2D thin films compatible with the efficient wet-chemical etching process represent realistic advancement toward new-generation integrated functional devices. Here, thickness-controllable growth and chemical patterning of high-quality Bi2O2Te continuous films are demonstrated. Noticeably, except for an ultrahigh mobility (∼45074 cm2 V-1 s-1 at 2 K) and obvious Shubnikov-de Hass quantum oscillations, a 2D transport channel and large linear magnetoresistance are revealed in the patterned Bi2O2Te films. Investigation implies that the linear magnetoresistance correlates with the inhomogeneity described by P. B. Littlewood's theory and EMT-RRN theory developed recently. These results not only reveal the nonsaturating linear magnetoresistance in high-quality Bi2O2Te but shed light on understanding the corresponding physical origin of linear magnetoresistance in 2D high-mobility semiconductors and providing a pathway for the potential application in multifunctional electronic devices.

Direction control of electromagnetic beam scattering by physically stacked cascaded coding metasurfaces

Coded metasurfaces build a bridge between the physical world and digital worlds, making it possible to manipulate electromagnetic waves and implement programmable metamaterials through digitally coded sequences. This “digital metasurface” based on binary digital logic greatly simplifies the design process of the metasurface and improves the flexibility of regulating electromagnetic waves. Based on the principle of Fourier convolution addition, a physical superposition cascaded metasurface is designed. The metasurface unit consists of three dielectric substrates and four “H”-shaped copper metal patch boards. The addition of most coding metasurfaces is to add two basic coding metasurfaces through the addition rules between digital codes to obtain a new coding sequence, and the new coding sequence has the characteristics of the previous two coding sequences. We propose a physically superimposed cascaded encoding metasurface. By physically superposing two different sequences of metasurfaces, the cascaded metasurface formed after superposition also has the characteristics of the first two basic coding sequences. We experimentally verified the proposed idea using two different dielectric materials, and there was good consistency between the experiment and simulation, thereby verifying the consistency of the metasurface cascade and the phase-encoding element surface addition principle. This design approach has potential applications in multifunctional photonic devices.

Mn dopant-enabled BiFeO3 with enhanced magnetic and photoelectric properties

In this study, BiFe1−XMnXO3 (BFMXO, x = 0, 0.03, 0.05, 0.07, 0.10, and 0.15) nanoparticles were synthesized using the sol-gel technique. The XRD patterns confirm that the BFMXO nanoparticles exhibit a rhombic structure with the addition of Mn dopant, while structural distortion occurred as the doping concentration increased. In particular, Mn doping effectively induced lattice shrinkage and enhanced the lattice strain. The SEM and TEM images showed increased uniformity and grain size reduction as Mn doping concentration increased. The XPS spectra show that the conversion of Fe2+ to Fe3+ leads to the increase of oxygen vacancy concentration. Further, the M−H loops show that the saturation magnetization and residual magnetization of all Mn-doped samples were successfully improved with the gradual transformation from antiferromagnetism to ferromagnetism. Therefore, BiFe0.93Mn0.07O3 reached a maximum Ms and Mr of approximately 0.956 and 0.054 emu/g, respectively. Further, BiFe0.93Mn0.07O3 exhibited 4–5 times higher photoconductivity than the pristine sample. First-principles calculations further accounted for the improved magnetic and electrical properties of BFMXO induced by the Mn dopant. This study demonstrates an effective method for controlling the structure and characteristics of BFO-based nanomaterials for multifunctional device applications.

Room-Temperature, Nanoscale Multiferroic Pb(Fe0.5Ta0.5)1−x(Zr0.53Ti0.47)xO3 (x = 0.2, 0.3) Thin Films Grown via the Pulsed Laser Deposition Technique

Multiferroic materials capable of robust magnetoelectric coupling at room temperature are currently being explored for their possible multifunctional device applications. Highly (100)-oriented Pb(Fe0.5Ta0.5)x(Zr0.53Ti0.47)1−x (PZTFTx) thin films (x = 0.2 and 0.3) with a thickness of about 300 nm were grown on La0.67Sr0.33CoO3 (LSCO)-buffered MgO 100-oriented substrates via the pulsed laser deposition method. An analysis of their X-ray diffraction patterns suggests the stabilization of the orthorhombic phase in the thin films at room temperature. Dielectric spectroscopic measurements of the metal–insulator–metal (Pt/PZTFTx/LSCO) thin-film capacitors as a function of temperature revealed a diffuse ferroelectric-to-paraelectric phase transition around Tm ~520 and 560 K for the x = 0.2 and 0.3 thin films, respectively. Well-saturated electrical hysteresis loops with large remanent (Pr) and saturation (Ps) polarizations were observed in these capacitors, which indicates the establishment of intrinsic ferroelectric ordering in the thin films at room temperature. These thin films retained ferromagnetic/ferrimagnetic ordering up to 300 K and showed saturation magnetization values of 8.3 (x = 0.2) and 6.1 (x = 0.3) emu/cm3 at room temperature. The magnetoelectric coupling constants of 2040 mV/cmOe (x = 0.2) and 850 mV/cmOe (x = 0.3), respectively, were obtained at an in-plane bias field at room temperature. The present study demonstrates that PZTFTx thin films are multiferroic at room temperature with large magnetoelectric couplings, and these materials may be suitable for use in magnetic sensors and spintronic device applications.

Magnetic Ni‐Nanoinclusions in VO2 Thin Films for Broad Tuning of Phase Transition Properties

AbstractMott insulator VO2 exhibits an ultrafast and reversible semiconductor‐to‐metal transition (SMT) near 340 K (67 °C). In order to fulfill the multifunctional device applications, effective transition temperature (Tc) tuning as well as integrated functionality in VO2 is desired. In this study, multifunctionalities including tailorable SMT characteristics, ferromagnetic (FM) integration, and magneto‐optical (MO) coupling, have been demonstrated via metal/VO2 nanocomposite designs with controlled morphology, i.e., a two‐phase Ni/VO2 pillar‐in‐matrix geometry and a three‐phase Au/Ni/VO2 particle‐in‐matrix geometry. Evident Tc reduction of 20.4 to 54.9 K has been achieved by morphology engineering. Interestingly, the Au/Ni/VO2 film achieves a record‐low Tc of 295.2 K (22.2 °C), slightly below room temperature (25 °C). The change in film morphology is also correlated with unique property tuning. Highly anisotropic magnetic and optical properties have been demonstrated in Ni/VO2 film, whereas Au/Ni/VO2 film exhibits isotropic properties because of the uniform distribution of Au/Ni nanoparticles. Furthermore, a strong MO coupling with enhanced magnetic coercivity and anisotropy is demonstrated for both films, indicating great potential for optically active property tuning. This demonstration opens exciting opportunities for the VO2‐based device implementation towards smart windows, next‐generation optical‐coupled switches, and spintronic devices.

Correlation of magnetic and dielectric relaxation to perovskite/spinel structural phase transition in Bi0.9La0.1FeO3–Fe3O4 bi-phase composites

Nanocomposites are widely investigated nowadays due to their vast applications in multifunctional devices. La-doped Bi0.9FeO3 is considered as potential candidate to be utilized in multiferroic applications. However, limitations of this composition include weak magnetic and magnetoelectric response. To overcome weak magnetic response of this material, a series of nanocomposite samples is presented here by combining it with optimized Fe3O4 contents. X-ray diffraction patterns confirm the cubic structure of Fe3O4 belonging to space group Fd3‾m and the rhombohedral-type perovskite crystal structure of Bi0.9La0.1FeO3 having space group R3m. Field emission scanning electron microscopy reveals spherical shapes of nanograins. High dielectric constant with fewer energy losses revealed for pure Bi0.9La0.1FeO3 composition, while saturation magnetization and remanent magnetization were increased with the addition of Fe3O4 phase into Bi0.9La0.1FeO3. Enhanced magnetic properties with moderate dielectric properties of 0.6Bi0.9La0.1FeO3+0.4Fe3O4 make it a prominent and potential candidate to be utilized in memory storage devices.

Cr3+ doping-controlled magnetic and dielectric properties of polycrystalline Y-type BaSrCo2Fe11-xCrxAlO22 hexaferrite

The trend towards multifunctionality and integrating electronic devices has led to the exploration of Y-type hexaferrite with excellent magnetic and dielectric properties. The Y-type hexaferrite BaSrCo2Fe11-xCrxAlO22 (0.0 ≤ x ≤ 0.5, with step of 0.1) ceramics have been prepared by conventional solid state reaction route. The phase structure, microscopic morphology, magnetic and dielectric properties of Y-type hexaferrite with chromium substitution are studied in detail. The analysis of XRD, SEM and EDS reveals that the lattice parameters and grain size decrease with the increase of Cr content. XPS results show the coexistence of Fe2+ and Fe3+. All samples exhibit well-defined ferromagnetic hysteresis loops at room temperature and the Cr3+ doping enhances the saturation magnetization and coercivity. The dielectric constants for all samples are found in the range of 10–15 and the dielectric loss is less than 0.02 at high frequency. The resistivity demonstrates that the samples possess high insulating nature with all above 2 × 109 Ω·cm, with a maximum value of 9.5 × 109 Ω·cm for x = 0.2. These results reveal that Cr3+ doped Y type hexaferrite could have potential applications in multifunctional electronic devices.

Superhard BN allotropes with tunable hybridization sp2/sp3 ratios by compressed nanotubes

The superhard BN materials with tunable properties present potential applications in multifunctional devices under extreme conditions. Eight novel BN structures of which band gaps ranging from 2.34 to 6.18 eV due to the tunable hybridization sp2/sp3 ratios, are proposed by the polymerization of BN nanotubes (BNNTs), including two fully sp2 hybridization structures (tP14-BN and tP16-BN), two fully sp3 hybridization structures (hP24-BN and hP48-BN) and four sp2/sp3 hybridization structures (mP44-BN, oI28-BN, mP76-BN and mP84-BN). There are four superhard sp2/sp3 BN (B:N = 1:1) structures are the firstly reported. Notably, the mP76-BN with the hardness of 52.55 GPa is the hardest structure in all the reported sp2/sp3 hybrid BN structures. Moreover, the oI28-BN, mP76-BN and mP84-BN exhibit the high fracture toughness property. This study systematically reveals the transition mechanism of BNNTs under high pressure and theoretically presents an efficient route to modulate the sp2/sp3 hybridization ratios in superhard BN allotropes realizing tunable band gaps for the potential applications in electronic devices or mechanical materials.

Piezoelectric altermagnetism and spin-valley polarization in Janus monolayer Cr2SO

Altermagnetism can achieve spin-split bands in collinear symmetry-compensated antiferromagnets. Here, we predict altermagnetic order in Janus monolayer Cr2SO with eliminated inversion symmetry, which can realize the combination of piezoelectricity and altermagnetism in a two-dimensional (2D) material, namely, 2D piezoelectric altermagnetism. It is found that Cr2SO is an altermagnetic semiconductor, and the spin-split bands of both valence and conduction bands are near the Fermi level. The Cr2SO has large out-of-plane piezoelectricity (|d31| = 0.97 pm/V), which is highly desirable for ultrathin piezoelectric device application. Due to spin-valley locking, both spin and valley can be polarized by simply breaking the corresponding crystal symmetry with uniaxial strain. Our findings provide a platform to integrate spin, piezoelectricity, and valley in a single material, which is useful for multi-functional device applications.

Tailoring the anisotropic effect of Janus In2 XY (X/Y = S, Se, Te) monolayers toward realizing multifunctional optoelectronic device applications

Anisotropic effect of two-dimensional materials remains one of the most attractive properties, introducing an additional degree of freedom for tuning physical performances. In this work, we investigate the anisotropies of electronic, transport, piezoelectric, and optoelectronic properties of Janus In2 XY (X/Y = S, Se, Te) monolayers (J-In2 XY MLs) by performing first-principles calculations. We find that such J-In2 XY MLs possess moderate bandgap (2.07–2.29 eV), high carrier mobility (∼103 cm−2V−1s−1), visible light absorption (∼105 cm−1), large out-of-plane piezoelectric response and ultra-soft mechanical nature . We construct a kind of J-In2 XY-based phototransistor to investigate the optoelectronic properties under linearly polarized light. We find that the low recombination probability of photogenerated carriers ensured by anisotropic effect enhances the photocatalytic potential of J-In2 XY MLs. And the pivotal role induced by anisotropy in photocurrent can cause a prominent on/off ratio (∼100), considerable responsivity (0.038 AW−1, 0.036 AW−1) and external quantum efficiency (10.6%, 11.5%). Our study provides an avenue for the design of future anisotropic J-In2 XY-based multifunctional optoelectronic device.

Prediction of tunable room-temperature ferromagnetism, ferroelectricity, and ferroelasticity in a CrNCl monolayer

Two-dimensional (2D) multiferroic materials combining intrinsic ferroelectricity, ferromagnetism, and ferroelasticity, which promise piezo-magnetoelectric effects, are highly desired for their potential applications in high-density and multi-functional spintronic devices. However, a room-temperature 2D triferroic semiconductor has never been reported. Here, on the basis of first-principle calculations, we predict that the CrNCl monolayer is a potential 2D triferroic semiconductor with ferroelectricity, ferromagnetism, and ferroelasticity coexisting and strongly coupling at room temperature. The strong d-p hybridizations between Cr and N ions give rise to Cr–N dimerizations, leading to spontaneous symmetry-breaking and an in-plane electric polarization, as well as a remarkable enhancement of ferromagnetic super-exchange interactions. Moreover, the ferroelastic transition is accompanied by a 90° rotation of the in-plane electric polarization and the magnetic easy axis, suggesting a strong piezo-magnetoelectric effect. These findings provide insights into multiferroic behaviors in 2D systems and can help facilitate further advancements in spintronics.

Influence of Te-Incorporated LaCoO3 on Structural, Morphology and Magnetic Properties for Multifunctional Device Applications.

A high perovskite activity is sought for use in magnetic applications. In this paper, we present the simple synthesis of (2.5% and 5%) Tellurium-impregnated-LaCoO3 (Te-LCO), Te and LaCoO3 (LCO) by using a ball mill, chemical reduction, and hydrothermal synthesis, respectively. We also explored the structure stability along with the magnetic properties of Te-LCO. Te has a rhombohedral crystal structure, whereas Te-LCO has a hexagonal crystal system. The reconstructed Te was imbued with LCO that was produced by hydrothermal synthesis; as the concentration of the imbuing agent grew, the material became magnetically preferred. According to the X-ray photoelectron spectra, the oxidation state of the cobaltite is one that is magnetically advantageous. As a result of the fact that the creation of oxygen-deficient perovskites has been shown to influence the mixed (Te4+/2-) valence state of the incorporated samples, it is abundantly obvious that this process is of utmost significance. The TEM image confirms the inclusion of Te in LCO. The samples start out in a paramagnetic state (LCO), but when Te is added to the mixture, the magnetic state shifts to a weak ferromagnetic one. It is at this point that hysteresis occurs due to the presence of Te. Despite being doped with Mn in our prior study, rhombohedral LCO retains its paramagnetic characteristic at room temperature (RT). As a result, the purpose of this study was to determine the impacts of RT field dependency of magnetization (M-H) for Te-impregnated LCO in order to improve the magnetic properties of RT because it is a low-cost material for advanced multi-functional and energy applications.

Sensing characterization of an amorphous PDMS/Ecoflex blend composites with an improved interfacial bonding and rubbing performance

In this paper, a polymer blend labeled PDMS/Ecoflex (PE) was fabricated using Polydimethylsiloxane (PDMS) and Ecoflex 00-30 in various proportions. An innovative carbon nanotube/carbon black (CNT/CB) hybrid filler reinforced cetyltrimethylammonium bromide (CTAB) surfactant was prepared and sprayed to obtain CNT/CB/PE composite material. The resulting PE blend matrix showed excellent mechanical properties, including high stretchability of nearly 500% strain, minimal hysteresis, and reduced friction by up to 75% with decreasing wear. These properties were attributed to the combined effect of Young’s modulus, stiffness, and hardness of PDMS and Ecoflex. Additionally, three types of contacts CNT-CB, CB-CB, and CNT-CNT were produced by the favorable interaction of CNT and CB particles, stabilizing the sensor signal. The CNT/CB/PE sensor had an improved wear resistance, conductivity stabilization, stretchability, gauge factor during the tensile test, and strain-dependent sensitivity across a broad range of fixed strains (up to 100% strain). Furthermore, the sensor was attached to various human body joints to track the related human motions, proving the fascinating perspective in detecting varioushuman movements and making it appropriate for application in multifunctional wearable devices in hostile environments.

Topological interface states by energy hopping within power-law variable section waveguides

An energy-hopping one-dimensional acoustical topology within power-law variable section waveguides is proposed in this paper, wherein a topological phase transition results from the energy in the basic unit hopping to the nearby unit, with the same energy mode causing its energy band to first close and then open. This study can achieve improved sound energy at the topological interface state and further regulate sound energy based on enhanced sound energy. The large open hole determines the wide frequency range where the designable topological interface state is constructed and the power law of the curve of the structure can adjust the size of the common forbidden band of the two topological states to further improve the bandwidth. The small open hole regulates the magnitude of the acoustic energy at the topological interface state. This research will provide guidance for designing acoustic devices with different frequencies and different acoustic energy concentrations and realizing engineering applications of other multifunctional acoustic devices.

α-In2Se3 Nanostructure-Based Photodetectors for Tunable and Broadband Response

The strong thickness-dependent narrow direct band gap of few-layer α-In2Se3 makes it a promising candidate for high-performance photodetectors. However, few researchers focus on the relationship between thickness and optoelectronic characteristics, and most results are based on the mechanically exfoliated α-In2Se3 nanoflakes. Herein, a reliable physical vapor deposition strategy to grow α-In2Se3 nanosheets with tunable thickness and submillimeter scale is reported. High-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) studies confirmed the high-quality growth of α-In2Se3 nanosheets. The back-gate field-effect transistors on SiO2 substrates display n-type semiconductor behavior. A systematical investigation of the optoelectronic properties reveals a thickness-dependent broadband response from visible (447 nm) to near-infrared (1550 nm) wavelengths with better and excellent performance obtained in thicker α-In2Se3 nanosheets than that in thinner devices. More importantly, a great improvement of the responsivity, detectivity, and external quantum efficiency (EQE) can be achieved by changing the thickness of In2Se3. The photodetector exhibits an outstanding photoresponsivity of 347.6 A/W, an ultrahigh detectivity of 1.5 × 1013 Jones, and an external quantum efficiency of 8.3 × 104%, which is superior to several α-In2Se3 nanostructure- or other two-dimensional (2D)-based photodetectors. The thickness-dependent broadband response characteristics make the α-In2Se3 nanostructure a promising candidate for multifunctional optoelectronic device applications.