Effective Non-Radiative Interfacial Recombination Suppression Scenario Using Air Annealing for Antimony Triselenide Thin-Film Solar Cells.

Antimony triselenide (Sb2Se3) has become a very promising candidate for next-generation thin-film solar cells due to the merits of their low-cost, low-toxic and excellent optoelectronic properties. Despite Sb2Se3 thin-film photovoltaic technology having undergone rapid development over the past few years, insufficient doping concentration and severe recombination have been the most challenging limitations hindering further breakthroughs for the Sb2Se3 solar cells. Post-annealing treatment of the Sb2Se3/CdS heterojunction was demonstrated to be very helpful in improving the device performance previously. In this work, post-annealing treatments were applied to the Sb2Se3/CdS heterojunction under a vacuum and in the air, respectively. It was found that compared to the vacuum annealing scenario, the air-annealed device presented notable enhancements in open-circuit voltage. Ultimately a competitive power conversion efficiency of 7.62% was achieved for the champion device via air annealing. Key photovoltaic parameters of the Sb2Se3 solar cells were measured and the effects of post-annealing treatments using different scenarios on the devices were discussed.

Directional Scattering Switching from an All-Dielectric Phase Change Metasurface.

All-dielectric metasurfaces are a blooming field with a wide range of new applications spanning from enhanced imaging to structural color, holography, planar sensors, and directionality scattering. These devices are nanopatterned structures of sub-wavelength dimensions whose optical behavior (absorption, reflection, and transmission) is determined by the dielectric composition, dimensions, and environment. However, the functionality of these metasurfaces is fixed at the fabrication step by the geometry and optical properties of the dielectric materials, limiting their potential as active reconfigurable devices. Herein, a reconfigurable all-dielectric metasurface based on two high refractive index (HRI) materials like silicon (Si) and the phase-change chalcogenide antimony triselenide (Sb2Se3) for the control of scattered light is proposed. It consists of a 2D array of Si-Sb2Se3-Si sandwich disks embedded in a SiO2 matrix. The tunability of the device is provided through the amorphous-to-crystalline transition of Sb2Se3. We demonstrate that in the Sb2Se3 amorphous state, all the light can be transmitted, as it is verified using the zero-backward condition, while in the crystalline phase most of the light is reflected due to a resonance whose origin is the contribution of the electric (ED) and magnetic (MD) dipoles and the anapole (AP) of the nanodisks. By this configuration, a contrast in transmission (ΔT) of 0.81 at a wavelength of 980 nm by governing the phase of Sb2Se3 can be achieved.

Numerical Simulation of the Performance of Sb2Se3 Solar Cell via Optimizing the Optoelectronic Properties Based SCAPS-1D.

Antimony trisulfide (Sb2Se3), a non-toxic and accessible substance, has possibilities as a material for use in solar cells. The current study numerically analyses Sb2Se3 solar cells through the program Solar Cell Capacitance Simulator (SCAPS). A detailed simulation and analysis of the influence of the Sb2Se3 layer's thickness, defect density, band gap, energy level, and carrier concentration on the devices' performance are carried out. The results indicate that a good device performance is guaranteed with the following values in the Sb2Se3 layer: an 800 optimal thickness for the Sb2Se3 absorber; less than 1015 cm-3 for the absorber defect density; a 1.2 eV optimum band gap; a 0.1 eV energy level (above the valence band); and a 1014 cm-3 carrier concentration. The highest efficiency of 30% can be attained following optimization of diverse parameters. The simulation outcomes offer beneficial insights and directions for designing and engineering Sb2Se3 solar cells.

Distinctive Deep-Level Defects in Non-Stoichiometric Sb2 Se3 Photovoltaic Materials.

Characterizing defect levels and identifying the compositional elements in semiconducting materials are important research subject for understanding the mechanism of photogenerated carrier recombination and reducing energy loss during solar energy conversion. Here it shows that deep-level defect in antimony triselenide (Sb2 Se3 ) is sensitively dependent on the stoichiometry. For the first time it experimentally observes the formation of amphoteric SbSe defect in Sb-rich Sb2 Se3 . This amphoteric defect possesses equivalent capability of trapping electron and hole, which plays critical role in charge recombination and device performance. In comparative investigation, it also uncovers the reason why Se-rich Sb2 Se3 is able to deliver high device performance from the defect formation perspective. This study demonstrates the crucial defect types in Sb2 Se3 and provides a guidance toward the fabrication of efficient Sb2 Se3 photovoltaic device and relevant optoelectronic devices.

Excitonic and electronic transitions in Me-Sb2Se3 structures.

The optical anisotropy of the Sb2Se3 crystals was investigated at 300 and 11 K. Excitonic features of four excitons (A, B, C, and D) were observed in the optical spectra of the Sb2Se3 single crystals and in the photoelectric spectra of the Me-Sb2Se3 structures. The exciton parameters, such as the ground (n = 1) and excited (n = 2) state positions and the binding energy (Ry), were determined. The effective mass of the electrons at the bottom of the conduction band (m c * = 0.67m 0) as well as the holes at the four top valence bands (m v1 * = 3.32m 0, m v2 * = 3.83m 0, m v3 * = 3.23m 0 and m v4 * = 3.23m 0) were calculated in the Г-point of the Brillouin zone. The magnitude of the valence band splitting V1-V2 due to the spin-orbit interaction (Δso = 35 meV) and the crystal field (Δcf = 13 meV) were estimated in the Brillouin zone center. The energy splitting between the bands V3-V4 was 191 meV. The identified features were discussed based on both the theoretically calculated energy band structure and the excitonic band symmetry in the Brillouin zone (k = 0) for crystals with an orthorhombic symmetry (Рnma). The photoelectric properties of the Me-Sb2S3 structures were investigated in the spectral range 1-1.8 eV under E||c and E⟂c polarization conditions and at different applied voltages.

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.

Controlled Electrodeposition of Photoelectrochemically Active Amorphous MoS x Cocatalyst on Sb2Se3 Photocathode.

Amorphous molybdenum sulfide (a-MoS x) is a promising hydrogen evolution catalyst owing to its low cost and high activity. A simple electrodeposition method (cyclic voltammetry) allows uniform formation of a-MoS x films on conductive surfaces. However, the morphology of a-MoS x deposited on a TiO2/Sb2Se3 photocathode could be modulated by varying the starting potential. The cathodically initiated a-MoS x showed conformal filmlike morphology, whereas anodic initiation induced inhomogeneous particulate deposition. The filmlike morphology of a-MoS x was subjected to catalyst activation, which improved the photocurrent density and reduced the charge-transfer resistance at the semiconductor/electrolyte interface, as compared to that of its particulate counterpart. X-ray photoelectron spectroscopy confirmed that different chemical states of a-MoS x (photoelectrochemically active sites) were developed on the basis of the electrodeposited a-MoS x morphology. The research provides an effective approach for uniformly depositing cost-effective a-MoS x on nanostructured photoelectrodes, for photoelectrochemical water splitting.

Ultralong Sb2Se3 Nanowire-Based Free-Standing Membrane Anode for Lithium/Sodium Ion Batteries.

Metal chalcogenides have emerged as promising anode materials for lithium ion batteries (LIBs) and sodium ion batteries (SIBs). Herein, a free-standing membrane based on ultralong Sb2Se3 nanowires has been successfully fabricated via a facile hydrothermal synthesis combined with a subsequent vacuum filtration treatment. The as-achieved free-standing membrane constructed by pure Sb2Se3 nanowires exhibits good flexibility and integrity. Meanwhile, we investigate the lithium and sodium storage behavior of the Sb2Se3 nanowire-based free-standing membrane. When applied as the anode for LIBs, it delivers a reversible capacity of 614 mA h g-1 at 100 mA g-1, maintaining 584 mA h g-1 after 50 cycles. When applied as the anode for SIBs, it delivers a reversible capacity of 360 mA h g-1 at 100 mA g-1, retaining 289 mA h g-1 after 50 cycles. Such difference in electrochemical performance can be attributed to the more complex sodiation process relative to the corresponding lithiation process. This work may provide insight on developing Sb2Se3-based anode materials for high-performance LIBs or SIBs.