Sb2Se3 Layers Research Articles

Insights on the Thermal Stability of the Sb2Se3 Quasi‐1D Photovoltaic Technology

This work explores the thermal stability of antimony‐based photovoltaic (PV) technologies investigating the effect of low‐temperature (50—350 °C) postdeposition annealings (PDAs) on bare Sb2Se3 absorbers and complete SLG/Mo/Sb2Se3/CdS/i‐ZnO/ITO devices (5.7% power conversion efficiency with no anti‐reflecting coating or metallic grid). A comprehensive structural analysis by means of X‐ray diffraction and Raman spectroscopy, coupled with optoelectronic characterization, reveals clear evidences of a degradation process dominated by selenium diffusion. The degradation process is observed to start at low PDA temperatures as a shrinkage of the Sb2Se3 unit cell. Further increasing the PDA temperature above 200 °C leads to the formation of Sb oxides and Se secondary phases in bare absorbers, and of CdS1—x Se x in complete devices at the Sb2Se3 front interface which completely degrade the heterojunction and kill device performance. Furthermore, a clear correlation is found between PV performance decrease and Sb2Se3 layer lattice shrinkage with the increasing PDA temperature (T > 50 °C). This is the first time that thermal instability is reported for the Sb2Se3 compound at temperatures commonly used during PV module fabrication processes such as emitter/transparent conducting oxide deposition or encapsulation.

Band alignment of Sb2O3 and Sb2Se3

Antimony selenide (Sb2Se3) possesses great potential in the field of photovoltaics (PV) due to its suitable properties for use as a solar absorber and good prospects for scalability. Previous studies have reported the growth of a native antimony oxide (Sb2O3) layer at the surface of Sb2Se3 thin films during deposition and exposure to air, which can affect the contact between Sb2Se3 and subsequent layers. In this study, photoemission techniques were utilized on both Sb2Se3 bulk crystals and thin films to investigate the band alignment between Sb2Se3 and the Sb2O3 layer. By subtracting the valence band spectrum of an in situ cleaved Sb2Se3 bulk crystal from that of the atmospherically contaminated bulk crystal, a valence band offset (VBO) of −1.72 eV is measured between Sb2Se3 and Sb2O3. This result is supported by a −1.90 eV VBO measured between Sb2O3 and Sb2Se3 thin films via the Kraut method. Both results indicate a straddling alignment that would oppose carrier extraction through the back contact of superstrate PV devices. This work yields greater insight into the band alignment of Sb2O3 at the surface of Sb2Se3 films, which is crucial for improving the performance of these PV devices.

Tandem photoelectrochemical and photoredox catalysis for efficient and selective aryl halides functionalization by solar energy

Tandem photoelectrochemical and photoredox catalysis for efficient and selective aryl halides functionalization by solar energy

A Novel Thermochemical Metal Halide Treatment for High-Performance Sb2Se3 Photocathodes.

The fabrication of cost-effective photostable materials with optoelectronic properties suitable for commercial photoelectrochemical (PEC) water splitting represents a complex task. Herein, we present a simple route to produce Sb2Se3 that meets most of the requirements for high-performance photocathodes. Annealing of Sb2Se3 layers in a selenium-containing atmosphere persists as a necessary step for improving device parameters; however, it could complicate industrial processability. To develop a safe and scalable alternative to the selenium physical post-processing, we propose a novel SbCl3/glycerol-based thermochemical treatment for controlling anisotropy, a severe problem for Sb2Se3. Our procedure makes it possible to selectively etch antimony-rich oxyselenide presented in Sb2Se3, to obtain high-quality compact thin films with a favorable morphology, stoichiometric composition, and crystallographic orientation. The treated Sb2Se3 photoelectrode demonstrates a record photocurrent density of about 31 mA cm−2 at −248 mV against the calomel electrode and can thus offer a breakthrough option for industrial solar fuel fabrication.

Evaluation of Cd1–x Zn x S as electron transport layer in superstrate and inverted configurations of Sb2Se3 solar cells with n-i-p structure

In this work, we evaluate the role of the ternary compound, Cd1–x Zn x S, as an electron-transport layer (ETL) in the n-i-p structure of antimony selenide (Sb2Se3) solar cells. The incorporation of Zn reduces the amount of Cd and contributes to improving the power-conversion efficiency of the solar cell. On the other hand, the n-i-p structure makes it possible to overcome two issues that impair the efficiency of Sb2Se3 solar cells: the potential barrier due to the rear contact and the low hole concentration in the Sb2Se3 absorber material. In this paper, we present a theoretical work on Sb2Se3 solar cells using the SCAPS 1-D software. The theoretical analysis allows us to understand the impact of the semiconductor parameters on efficiency and also to find the optimal values for an optimized device. The optimal molar composition of the ternary compound is investigated in the superstrate and inverted configurations. Parameters such as the thickness, defect density, and the acceptor concentration of the Cd1–x Zn x S and Sb2Se3 layers are optimized. Also, we analyze the impact of interface-defect density at the hole-transport layer (HTL) (Sb2Se3) and the ETL (Sb2Se3). Following optimization, a power-conversion efficiency (η) of 14.29% is obtained using Cd0.4Zn0.6S as the ETL and Cu2O as the HTL in the superstrate configuration. This simulation process is expected to guide other experimentalists in the design and manufacture of solar cells.

Crystallographic Orientation Control of 1D Sb2Se3 Nanorod Arrays for Photovoltaic Application by In Situ Back‐Contact Engineering

Low‐dimensional (LD) crystalline inorganic semiconductors have attracted increasing interest due to their unique electrical and optical properties. The crystallographic orientation in the LD films is one of the critical parameters that determine their strong anisotropic physical properties and device performance. Antimony selenide (Sb2Se3), a 1D crystalline semiconductor, is a promising absorber material for emerging photovoltaic technologies. The suitably oriented Sb2Se3 absorbers can offer excellent carrier transport and trap‐free grain boundaries, facilitating high‐efficiency devices. The crystallographic orientation of the Sb2Se3 light‐absorbing layer is found to be governed by the underlying layers, i.e., the back contact in substrate‐type solar cells. Herein, an in situ surface selenization treatment to the tungsten (W) back contact is applied to change the growth of Sb2Se3 layer from a layer‐like growth mode to an island‐like growth mode. As a result, highly [hk1]‐oriented Sb2Se3 nanorod arrays growing perpendicular to the W back‐contact surface are achieved. Moreover, the resulting tungsten selenide (WSe2) thin layer also acts as a hole transport layer and promotes hole extraction. Consequently, a conversion efficiency as high as 8.46% in Sb2Se3 solar cells with substrate configuration is achieved.

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 (OSe) and oxygen interstitial (Oi) 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.

Simulation of the Sb2Se3 solar cell with a hole transport layer

A model of the Sb2Se3 solar cell with a hole transport layer (HTL) has been investigated by solar cell capacitance simulator (SCAPS). The influence of different HTLs on device performance has been firstly analyzed, and CuO has been found to be the best HTL. Then, Sb2Se3 thickness, CuO thickness, the doping concentration of CuO, the hole mobility of CuO, the defect density of Sb2Se3 layer, the defect density at the CdS/Sb2Se3 interface, and the work function of metal electrode on device performance have been systematically studied. The optimum thicknesses of Sb2Se3 and CuO are 300 nm and 20 nm, respectively. To achieve ideal performance, the doping concentration of CuO should be more than 1019 cm−3, and its hole mobility should be over 1 cm2V−1 s−1. The defect densities in the Sb2Se3 layer and at the CdS/ Sb2Se3 interface play a critical role on device performance, both of which should be as low as 1013 cm−3 and 1014 cm−2, respectively. In addition, the work function of the metal electrode should be more than 4.8 eV to avoid formation of Schottky junction at the metal electrode interface. After optimization, a best efficiency of 23.18% can be achieved. Our simulation results provide valuable information to further improve the efficiency of Sb2Se3 solar cells in practice.

Direct Z scheme-fashioned photoanode systems consisting of Fe2O3 nanorod arrays and underlying thin Sb2Se3 layers toward enhanced photoelectrochemical water splitting performance

An elegant Z-scheme-fashioned photoanode consisting of Fe2O3 nanorod arrays and underlying thin Sb2Se3 layers was rationally constructed. The photocurrent density of the Sb2Se3-Fe2O3 Z-scheme photoanode reached 3.07 mA cm-2 at 1.23 V vs. RHE, three times higher than that of pristine Fe2O3 at 1.03 mA cm-2. An obvious cathodic shift of the photocurrent onset potential of about 200 mV was also observed. The transient photovoltage response demonstrates that the suitable band edges (ECB ∼ -0.4 eV and EVB ∼ 0.8 eV) of Sb2Se3, match well with Fe2O3 (ECB ∼ 0.29 eV and EVB ∼ 2.65 eV), permitting the photoexcited electrons on the conduction band of the Fe2O3 to transfer to the valence band of Sb2Se3, and recombine with the holes therein, thus allowing a high concentration of holes to collect in the Fe2O3 for water oxidation. The transient absorption spectra further corroborate that the built-in electric field in the p-n heterojunction leads to a more effective separation and a longer lifetime of the charge carriers.

Correction: Direct Z scheme-fashioned photoanode systems consisting of Fe2O3 nanorod arrays and underlying thin Sb2Se3 layers toward enhanced photoelectrochemical water splitting performance.

Correction for 'Direct Z scheme-fashioned photoanode systems consisting of Fe2O3 nanorod arrays and underlying thin Sb2Se3 layers toward enhanced photoelectrochemical water splitting performance' by Yong Zhou et al., Nanoscale, 2019, DOI: 10.1039/c8nr08292h.

Analysis of Sb2Se3/CdS based photovoltaic cell: A numerical simulation approach

Sb2Se3 is a promising earth-abundant and nontoxic material suitable for photovoltaic applications. In the present study, Sb2Se3/CdS heterojunction solar cells are numerical analyzed by the program SCAPS (Solar Cell Capacitance Simulator). The influence of thickness, hole mobility and defect density of Sb2Se3 layer, as well as the CdS layer thickness and the work function of back contact on the devices performance are simulated and analyzed in detail. Our studies show that, the optimal thickness for Sb2Se3 absorber and CdS buffer layer is 600 nm and 60 nm, respectively. The absorber defect density less than 1014 cm−3, interface defect density less than 108 cm−3 and hole mobility higher than 15 cm2/V.s in Sb2Se3 layer is required to guarantee good device performance. Meanwhile, the work function of back contact larger than 4.8 eV is beneficial. A maximum efficiency of 16.5% can be obtained after optimization of different parameters. The simulation results provide useful insights and guideline for the designing and fabricating of Sb2Se3 solar cells.

Self-powered, high-speed Sb2Se3/Si heterojunction photodetector with close spaced sublimation processed Sb2Se3 layer

Antimony selenide (Sb2Se3) has received great attention recently due to its excellent carrier transport capacity and special one-dimensional crystal structure. The Sb2Se3-based bulk heterojunctions have been applied for photovoltaic with great success, but its potential application to photodetector has not been explored yet. In this work, a self-powered, high-speed Sb2Se3/Si heterojunction photodetector is fabricated and investigated, where the Sb2Se3 layer is deposited through close spaced sublimation (CSS) technique. The photodetector exhibits detection performance with a responsivity of 0.34 A/W at zero bias voltage and a broad spectral range from 300 to 1100 nm. Ultrafast response rise and fall times of 86 and 96 μs, respectively, are obtained, which is significantly better than previous reports of Sb2Se3-based photodetectors. The high crystallographic quality of the CSS-processed Sb2Se3 thin films and the built-in field at the Sb2Se3/Si interface is responsible to the high response speed of Sb2Se3/Si heterostructural photodetectors. The high-speed and broadband response properties make the Sb2Se3/Si heterojunction photodetector have potential applications for next-generation optoelectric devices.

Thermal Evaporation of Sb2Se3 as Novel Counter Electrode for Dye‐Sensitized Solar Cells

AbstractSb2Se3 was fabricated with a facile atmospheric pressure thermal evaporation procedure as counter electrode (CE) for dye‐sensitized solar cells (DSSCs). The introduction of a carbon nanoparticle (CNP) film as substrate was proved to facilitate Sb2Se3 deposition, resulting in the formation of a Sb2Se3 layer on the surface of carbon nanoparticles (denoted as CNP‐Sb2Se3). Electrochemical characterizations demonstrate the intrinsic catalytic ability of Sb2Se3 and better electrocatalytic activity and stability of Sb2Se3 deposited on CNP film in catalyzing I3‐ reduction. Evaporation temperature was found to affect the electrocatalytic activity of CNP‐Sb2Se3 and a lower temperature of 400oC was proved to be better in our case. As a result, the best performing DSSC with CNP‐Sb2Se3 CE yields a power conversion efficiency of 6.26%, which is comparable to that based on Pt CE (6.47%).

Addendum to ‘‘New optical recording material for video disc system’’ [J. Appl. Phys. 54, 1256 (1983)

Previous work has established that the optical characteristics of Sb2Se3 films are influenced by an amorphous-crystalline transition at 170 °C. This paper comments on the change in optical characteristics in an optical recording material composed of Sb2Se3 and Bi2Te3 layers caused by alloying between the layers above 250 °C.