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Antimony sulfide (Sb 2 S 3) is an appealing one-dimensional light-harvesting material for thin-film solar cells due to the high absorption coefficient, suitable bandgap and abundance of constituent elements. The orientation of the Sb 2 S 3 thin film is considered as one of the most important factors affecting the performance of the device. According to the minimum energy principle, Sb 2 S 3 is prone to grow parallel to the substrate along the [hk0] orientation which is harmful to the device performance. On the other hand, [hk1]-oriented films are much more beneficial but additional processes such as annealing are often required. In this work, stoichiometric Sb 2 S 3 thin films consist of compact, highly [hk1]-oriented grains have been prepared via a self-assembled growth by magnetron sputtering and post-sulfurization. After carefully optimized the preparation process, a champion device (2.89% power conversion efficiency) was obtained with an open-circuit voltage of 696 mV and a short-circuit current density of 12.48 mA/cm2 under AM 1.5G solar radiation. Interestingly, the high open-circuit voltage of our device is already comparable to the state-of-the-art Sb 2 S 3 solar cells. This work demonstrates a great potential of the sputtering and post-sulfurization method in fabrication of high-efficiency substrate Sb 2 S 3 thin-film solar cells. [ABSTRACT FROM AUTHOR]

Cu2ZnSnS4 (CZTS) thin films were prepared by sputtering three sulfide targets at different sulfurization annealing temperatures from 550 to 600 ℃. The morphology, microstructure and optical-electrical properties of CZTS thin films were investigated. It was found that the crystal quality at the CZTS/Mo interface without intermediate layers was promising and the thickness of MoS2 was limited to within 90 nm. The expected results were achieved after 575 ℃ sulfurization annealing, indicating that sputtering three sulfide targets can compensate for part of the sulfur partial pressure in the sulfurization process. The measurements showed that CZTS thin film (called S2) sulfurized at 575 ℃ with a mobility of 282.7 cm2/V·s and a band gap of 1.49 eV had the best electrical and optical properties. The elemental depth profile showed that the composition in S2 was homogeneously distributed. Finally, the CZTS solar cell with an active area 0.8 cm2 was successfully fabricated and the conversion efficiency was 2.7%. The max external quantum efficiency exhibited a value of 79.7%. The short-circuit current density and open-circuit voltage of the device were 20.12 mA/cm2 and 381 mV, respectively. The relationship between the composition and the voltage deficit was also discussed. [ABSTRACT FROM AUTHOR]

Despite the striking progress toward improving the efficiencies of organic solar cells (OSCs) resulting from the development of nonfullerene acceptors (NFAs), there is a rising requirement of investigation of the molecular design for achieving photochemically stable NFAs. Herein, applying two isomeric NFA molecules a‐IDTBTRh and l‐IDTBTRh based on angular‐indaceno[2,1‐b:6,5‐b′]dithiophene (a‐IDT) and linear‐IDT (l‐IDT) as the central cores, the effects of molecular conformation, aggregation behavior, and environmental factors on their photooxidation degradation processes are systematically studied. It is found that tuning regioisomeric central cores on the molecular skeleton influences the backbone conformation and conjugation, resulting in the different optoelectronic properties and molecular stacking characteristics. A strong molecular aggregation dependence of the optical losses and degradation mechanics in the annealed neat films is also observed, and it is shown that l‐IDTBTRh is much more photostable than its less‐ordered core derivative, a‐IDTBTRh. Furthermore, the effects of external environmental stresses on photobleaching behaviors of the annealed thin films are studied systematically, highlighting the role of concentrated light in accelerating photooxidation of organic materials. The results not only provide a comprehensive insight into the photooxidation properties and attenuation mechanisms of organic materials, but also suggest guidelines to rationally select materials for stable OSCs. [ABSTRACT FROM AUTHOR]

A series of InSb thin films were grown on GaAs substrates by molecular beam epitaxy (MBE). GaSb/AlInSb is used as a compound buffer layer to release the strain caused by the lattice mismatch between the substrate and the epitaxial layer, so as to reduce the system defects. At the same time, the influence of different interface structures of AlInSb on the surface morphology of buffer layer is explored. The propagation mechanism of defects with the growth of buffer layer is compared and analyzed. The relationship between the quality of InSb thin films and the structure of buffer layer is summarized. Finally, the growth of high quality InSb thin films is realized. [ABSTRACT FROM AUTHOR]

• Fabrication of CZTS:Na/CdS with Na doping on the surface using spin coating method. • The typical cliff-like CBO were obtained to 0.25 eV for CZTS/CdS heterojunction and 0.1 eV for CZTS:Na/CdS. • Sodium doping improves the performance of CZTS solar cells. Alkali doping can suppress deleterious antisite defects in kesterite Cu 2 ZnSnS 4 (CZTS) and improve the open-circuit voltage. In this study, the effects of light Na-doping on the performance and the band alignment of CZTS/CdS thin-film solar cells were investigated. CZTS:Na thin films were fabricated by the spin coating with 10% Na doping on the surface of CZTS. The Na-doping led to the narrower FWHM and larger grain size. The hole concentration and the conductivity were improved due to the Na Zn shallow acceptor defects. In addition, Na-doping can improve the band alignment of absorber/buffer interface and inhibit SRH recombination by the Na passivation effect and the suppression of Sn Zn defects. The typical cliff-like conduction band offset (CBO) was reduced from 0.25 eV in CZTS:Na/CdS to 0.1 eV in CZTS/CdS heterojunction. CZTS:Na device exhibited a higher Voc of 653 mV than that of CZTS/CdS device. The maximum conversion efficiency reached 7.46%, increased by 44% after Na-doping. These results clarify the effect of Na-doping on the band structure of the heterojunction in CZTS solar cells and support a new aspect that synthesis of a surface-doping CZTS:Na absorber has great potential for future research. [ABSTRACT FROM AUTHOR]

In this work, the (Ag,Cu)2ZnSnS4 (ACZTS) thin films were fabricated via sputtering with a multi-target to form different layer stacks, i.e., (S1) ZnS/Sn/Cu/Ag/Mo,(S2) ZnS/Sn/Ag/Cu/Mo and (S3) ZnS/Ag/Sn/Cu/Mo. The stacked precursors were sulfurized through a soft annealing, followed by a two-step sulfurization in a chamber filled with N2 at standard atmospheric pressure. The x-ray photoelectron spectroscopy elemental profile showed a vertical non-uniform distribution of Ag in the film. Based on the results of scanning electron microscopy and electron probe microanalysis, Ag enrichment of the upper surface was beneficial for the grain size. Moreover, a dense, uniform surface could be obtained and the stability of the elemental composition could be maintained. After optimizing the order of the Ag layers, the efficiency of the solar cells increased from 1.30% to 3.65%, an improvement of 181%. The open circuit voltage is increased from 448 mV to 630 mV because of the reduced voids, increased grain size, and reduced CuZn antisite defects. [ABSTRACT FROM AUTHOR]

The epitaxy properties of GaAs-based GaSb thin films were investigated under different growth conditions to identify suitable smooth areas on GaSb epilayer surface for growing high-quality AlInSb metamorphic buffers. The results showed notable reduction in threading dislocation densities (TDDs) and hillocks densities (HDs) of GaSb buffer layer when the temperature of substrates rising to Tc (surface reconstruction conversion temperature) + 110 °C and growth rate decreasing to 0.25 mono layer per second (ML/s). These conditions led to gradual changes in GaSb epilayer surface morphologies from tiny hillocks to near-parallel steps. The AlInSb/GaSb compound buffers were studied by employing five different structures of AlInSb metamorphic buffer layers grown on optimized GaSb layers, and then analyzed by various analytical methods. The influence of various structural buffer layers on defects were evaluated in order to suppress the formation of defects. It was shown that the buffer layer with low-temperature interface layer and superlattice structure presents obvious inhibitory effects on defects. Among these, specimens with superlattice interface exhibits the lowest TDDs of 3.1 × 107 cm−2 and moderate HDs of 2.4 × 107 cm−2. [ABSTRACT FROM AUTHOR]

A 25 nm thick Ag thin film was sputtered between the Cu2ZnSnS4 (CZTS) absorber and Mo electrode to improve the back contact in CZTS solar cells. The CZTS absorber was fabricated via a cost-effective N,N-dimethylformamide-based solution method. X-ray diffraction and Raman spectroscopy demonstrated that Ag diffused into the CZTS and partially substituted Cu, which resulted in an increased lattice constant a and grain size. Ag doping of CZTS (ACZTS) reduced both the Sn-loss and the presence of voids. An ACZTS photovoltaic device (ITO/i-ZnO/CdS/ACZTS/Mo) was fabricated and showed higher EQE than the CZTS device over the wavelength range of 450–800 nm. The open circuit voltage increased (Voc) from 543 to 631 mV, the short circuit current density (Jsc) increased from 10.36 to 14.37 mA, and the efficiency increased from 2.02 to 3.43% after sputtering the Ag layer. This is mainly because Ag functions as a temporary protective layer that made a tighter combination between Mo and the CZTS absorber. [ABSTRACT FROM AUTHOR]

Cu2ZnSnS4 (CZTS) thin films were sputtered on Mo/glass substrates using Cu, Sn and ZnS targets and sulfurized at 570°C. The effect of a ZnO intermediate layer between CZTS and Mo on the microstructure, morphology and photovoltaic properties was investigated. Three samples with different ZnO thickness, named as S1 (10 nm), S2 (50 nm) and S3 (211 nm), had the identical composition ratio of Cu/(Zn + Sn) = 0.67 and Zn/Sn = 1.05 for kesterite structure. No obvious secondary phase such as SnS, SnS2 and ZnS was found. XRD showed no ZnO peak which indicated that the ZnO layer was completely sulfurized and converted to ZnS and CZTS. The ZnO intermediate layer significantly inhibited the formation of MoS2 and the decomposition of CZTS. A porous interlayer with many voids appeared at CZTS/Mo in S1 and S2 which originated from two different formations of CZTS and resulted in the inferior properties. The efficiency of CZTS solar cells without ZnO was only 2.7%, obviously below that of the three samples with ZnO. The Voc and Jsc of S3 was 625 mV and 12.6 mA cm−2 respectively, which resulted in the highest efficiency of 4.16% in three samples. The results in S3 illustrate that the ZnS layer was substituted completely by ZnO which can effectively improve CZTS/Mo contact and the photovoltaic properties. [ABSTRACT FROM AUTHOR]

The Cu2ZnSnS4 (CZTS) thin films were fabricated by sulfurization of radiofrequency magnetron sputtered Cu–Zn–Sn–O (CZTO) precursors. Here, we extend recent works in the field of fabricating CZTO precursors by a new approach sputtering ZnO/Sn/Cu targets. The effects of one-step and two-step annealing processes applied for CZTO precursors on the structure, morphology, optical, and electrical properties were investigated systematically. The preannealing step of fundamental phase formation in the sulfurization process was also discussed. The two-step annealing process was found to affect the composition of element Sn slightly but significantly improved crystallinity, CZTS/Mo interfacial conditions, surface roughness, and electrical properties. The two-step annealed CZTS thin films had excellent optical and electrical properties with an optical band gap of 1.51 eV, a hole concentration of 2.4 × 1017 cm−3, and a hole mobility of 1.97 cm2/(V⋅s). In addition, the CZTS/Mo interface with small grains and voids were significantly improved. CZTS-based solar cell devices were successfully fabricated. The characteristics of current–voltage (J–V) curves indicated that short-circuit currents had a tendency to increase with the improvement of CZTS/Mo interface and surface morphology. As a result, the device based on two-step annealed CZTS thin films exhibited better performance with an open-circuit voltage of 553 mV, short-circuit current of 7.2 mA⋅cm−2, a fill factor of 37.8%, and a conversion efficiency of 1.51%. [ABSTRACT FROM AUTHOR]

MnBi/FeCo thin film composites are synthesized by magnetron sputtering, the physical and crystal structures are confirmed by SEM and XRD. The magnetic properties are characterized by VSM. When the FeCo layer thickness is 2 and 4 nm, magnetic exchange coupling between MnBi and FeCo is demonstrated by enhanced maximum energy product in MnBi/FeCo thin films from the single hard phase of MnBi. When the FeCo thickness is further increased to 6 nm, the exchange coupling between MnBi and FeCo is destroyed in MnBi/FeCo thin films. This research explored a possible way to increase the maximum energy product of MnBi thin films. [ABSTRACT FROM AUTHOR]

Zirconium oxynitride thin films were deposited on the sapphire substrate by DC magnetron sputtering process, which was performed in argon/oxygen/nitrogen mixture gases with various flow rates of reactive gases (N+O). It was observed from XRD, Raman and XPS results that oxygen had a great effect not only on the composition but also on the structure of zirconium oxynitride films. Moreover, the electrical behavior of zirconium oxynitride thin film was investigated and correlated with their compositional and structural properties. For samples deposited at relatively low flow rate, the 2D-3D process dominates the electrical transport mechanism in a weakly localized regime. When the samples deposited at a relatively high-flow rate, the electronic transport is governed by thermal activation at the high temperatures. While a crossover from thermal activation conduction to Mott's variable hopping conduction (VRH) was observed at the lower temperature range. The experimental results demonstrate that the addition of a small amount of oxygen into the zirconium nitride films can be an effective way to optimize the compositional, structural as well as electrical conduction properties of zirconium oxynitride thin films. [ABSTRACT FROM AUTHOR]

The Na 2 S-treated CZTS/Mo interface in back contact of Cu2ZnSnS4 (CZTS) thin films solar cell was reported firstly. The CZTS thin films were deposited on Mo/Glass substrates by radio frequency magnetron sputtering using a copper-zinc-tin-sulfur composite target and annealed in a sulfur-free atmosphere. The element composition of excess-sulfur CZTS target was modified to Cu:Zn:Sn:S=4.12:1.61:1:17.65. The microstructure, morphology, optical and electrical properties of Cu2ZnSnS4 were analyzed. It was found that the sulfur-free annealing suppressed the formation of resistance MoS 2 layer at CZTS/Mo interface. The CZTS/Mo interface was treated in a Na 2 S solution which promoted a better crystallization of CZTS absorbing layer.The optical band gap (Eg) value were found to be approximately ~1.47 eV and ~1.50 eV for CZTS and Na:CZTS samples. Finally, the photovoltaic properties of ZnO/ITO/CdS/CZTS/Mo solar cells were investigated. The open circuit voltage increased from 510.28 to 622.16 mV which ascribes to the recombination center diminishing through Na passivation. The conversion efficiency was improved from 2.37% to 3.26% after Na 2 S-treated method. [ABSTRACT FROM AUTHOR]

The CdS film is one of the best candidates for the n-type buffer layer in Cu 2 ZnSnS 4 (CZTS) solar cells. However, the inappropriate band alignment at CdS/CZTS heterojunction result in the high barrier for the photogenerated carriers, which decrease the open-circuit voltage and the short-circuit current. In this paper, the crystallization and the optical bandgap of the Zn-doping Cd 0.6 Zn 0.4 S film fabricated by chemical bath deposition were studied. XRD showed that the lattice constant of hexagonal Cd 0.6 Zn 0.4 S decreased a little after Zn doping because of the shorter bond length of Zn–S. Photoluminescence and transmittance spectra showed the band gap of Cd 0.6 Zn 0.4 S thin film increased from 2.59 to 2.88 eV due to Burstein-Moss shift. The conduction band offset (CBO) obviously decreased from 0.51 eV in CZTS/CdS heterojunction to 0.27 eV in CZTS/Cd 0.6 Zn 0.4 S heterojunction which result in the short-circuit current increasing from 12.25 to 15.05 mA/cm2. The conversion efficiency (E ff) and fill factor (FF) of the solar cell based on CZTS/Cd 0.6 Zn 0.4 S were increased from 2.31% to 31.06 to 4.88% and 47.45, comparing to CZTS/CdS solar cell. • The effects of the Zn-doping Cd 0.6 Zn 0.4 S film fabricate of Cu 2 ZnSnS 4 thin film solar cells were studied in detail. • To our knowledge, the (CBO) decreased from 0.51 eV in CZTS/CdS heterojunction to 0.27 eV in CZTS/Cd 0.6 Zn 0.4 S heterojunction. • The best Eff. of the fabricated CZTS/Cd 0.6 Zn 0.4 S thin film solar cell is 4.88% with the V oc of 628 mV, J sc of 15.05 mA/cm2. [ABSTRACT FROM AUTHOR]

Laser-induced well-ordered and controllable wavy patterns are constructed in the deposited metal thin film. The micrometer-sized structure and orientation of the wavy patterns can be controlled via scanning a different size of rectangle laser spot on the films. Ordered patterns such as aligned, crossed, and whirled wave structures were designed over large areas. This patterning technique may find applications in both exploring the reliability and mechanical properties of thin films, and fabricating microfluidic devices. [ABSTRACT FROM AUTHOR]

To overcome the high friction coefficient and low toughness bottleneck of MoSi 2 used as protective films for moving parts, a novel strategy of doping and alloying through magnetron sputtering to build self-lubricating Mo-Si-Au solid solution film has been proposed. Herein, a series of MoSi 2 films with different Au contents were prepared, and their phase structure, mechanical and tribological properties were investigated. The results indicate that when Au/Mo atomic ratio R = 0.10, Au atoms tend to replace Si atoms to form Mo-Si-Au solid solution film. Nevertheless, the Au atom would segregate to form a nanocomposite at R = 0.20. The nanoindentation test shows that the Mo-Si-Au solid solution film possesses the largest hardness, which is mainly attributed to the solid solution strengthening. The result of tribological testing exhibits that Au doping can significantly reduce the friction coefficient of MoSi 2. More importantly, Mo-Si-Au solid solution film is realized with a lower coefficient of friction (∼0.08), which is ascribed to the formation of MoSiO x lubricating phase during the sliding induced solute Au atoms. Accordingly, the research would provide a considerable theoretical and technical foundation for the development of novel self-lubricating films with excellent mechanical properties. [ABSTRACT FROM AUTHOR]

Transition-metal nitrides (TMNs) can be widely applied as protective coatings for precision parts, and improving their key performance characteristics is essential to make them more robust and durable in harsh environments. High-performance TMNs require establishing the structure-property relationship, and structural modulation is an effective procedure for optimizing their properties. Herein, high hard Zr-Y-N solid solution structure film with trace of solute Y atom fabricated by reactive magnetron sputtering and demonstrated excellent lubricating behavior under the condition of based oil, as well as superior corrosion resistance in a 3.5 wt% NaCl solution. It should be noted that the solid solution Zr-Y-N film is 40.1 % harder than pure ZrN film due to solid solution strengthening, resulting in a hardness of 29.0 GPa. During the sliding process of tribological behavior, the synergistic effect of in-situ formation Y 2 O 3 and ZrO 2 lubricating phase on the Zr-Y-N worn surface would significantly reduce the friction coefficient to 0.019. Additionally, based on the results obtained from the impedance spectrum and polarization curve, solute Y can enhance the corrosion resistance of ZrN by its compact solid solution structure, resulting in a corrosion current of S1 (1.71 E−05 A/cm2) that is much lower than that of ZrN (1.05 E−04 A/cm2), which is an important factor in optimizing the comprehensive performance of ZrN films. The novel strategy would be to open a window for more significantly improving the hardness of TMNs-based film by incorporating solute Y atoms, thereby further improving lubricating behavior and corrosion resistance. • ZrYN solid solution film combines high hardness, self-lubrication, and corrosion resistance. • ZrYN solid solution film achieve high hardness due to solid solution strengthening. • Self-lubrication was realized due to the synergistic effect of Y 2 O 3 and ZrO 2. • The excellent corrosion resistance of ZrYN film was subscribed to compact structure. [ABSTRACT FROM AUTHOR]

Abstract: Mechanical coating technique (MCT) was used to fabricate Fe thin films on alumina balls. The influence of the processing parameters including the milling atmosphere and the rotation speed of planetary ball mill on the formation of the thin films was investigated. The results of SEM and EDS showed that Fe particles reacted with oxygen in the air atmosphere and the formed ferroferric oxide hindered the formation of the thin films. Rotation speed also had great influence. Continuous Fe thin films with an average thickness of about 10μm were formed during the milling operation at 300rpm. However, they could not be formed at 200 and 400rpm. Furthermore, the evolution of the thin films was also studied and analyzed. An evolution model was proposed to describe it. According to the model, the evolution fell into nucleation, growth of nuclei, formation of thin films and exfoliation. It was considered that mechanical interlocking played an important role in the formation of the thin films. [Copyright &y& Elsevier]

Abstract: In this work, different positive voltages of a pulsed waveform, time intervals and electrolyte stirring were used to prepare by anodization of pure titanium plates, a series of TiO2 thin films based on nanotubes with different morphologies and dimensions. Electrolyte stirring results in large size TiO2 nanotubes with uneven surface morphology and less oriented directions. The titanium plates containing the TiO2 thin films were further annealed at 450°C for 30min under air. It was found that only crystalline anatase was formed under this condition. Both methylene blue degradation and antibacterial tests against Escherichia coli were performed to evaluate the photocatalytic performance of these TiO2 films. Better methylene blue degradation ability was achieved by TiO2 nanotubes prepared under electrolyte stirring. However, the antibacterial ability of the annealed TiO2 nanotubes was affected by their inner diameter rather than their length. It is also concluded that the anodized TiO2 nanotube arrays fabricated in this work are promising for photo-induced methylene blue degradation and bacteria killing applications. [Copyright &y& Elsevier]

CZTS precursors was deposit by sputtering, and then annealed in the range of 1000–5000 Pa sulfur partial pressure. The partial pressure of sulfur is controlled by changing the amounts of sublimed sulfur in a small, sealed quartz tube. As the sulfur partial pressure increased, the crystallinity of CZTS thin film was improved; surface voids and secondary phases were reduced; the thickness of MoS 2 at low sulfur partial pressure ranging from 1000 Pã3000 Pa. After the sulfur partial pressure reaching 5000 Pa, the thickness of MoS 2 increased significantly. The secondary phases, voids and MoS 2 reduced the carrier collection in the 500–800 nm wavelength range, resulting in lower short-circuit current density and fill factor. Finally, the device based on the 3000 Pa sulfur partial pressure achieved the highest photoelectric conversion efficiency of 4.25% (V OC : 0.648 V, I SC : 15.25 mA/cm2, FF : 43.02%). [ABSTRACT FROM AUTHOR]

• InAs interface layer can neutralize the accumulation of Sb elements in the GaSb/InAsSb interface. • The nucleation layer with low growth rate facilitated the coalescence process of mound during the growth of InAsSb layer. • The AlSb nucleation layer changed the generation mode of edge dislocations and reduced the dislocation density. • AlSb/GaSb SL buffer layer inhibited the propagation of dislocation by intersecting and closing them. In this account, a series of InAsSb thin films were grown on GaAs substrates with GaSb as buffer layer by MBE, the effect of nucleation layer grown under different conditions on the quality of InAsSb thin films was studied, and the inhibition effect of AlSb/GaSb superlattice structure (SLS) on defect propagation in heteroepitaxy was evaluated. In this process, the corresponding Sb/As BEP flux ratio changes of As/In BEP flux ratio are studied. The sensitivity of Sb/As BEP flux ratio to As beam change is eliminated by using locked As beam value and Sb/As BEP flux ratio, which improves the repeatability of epitaxial material component control. At the same time, the Sb content of the GaSb/InAsSb interface could be accurately tuned by controlling the opening sequence and time of the sources cell shutter. Released the increase of strain at the interface caused by too large Sb component. It can be used to control the composition of InAsSb materials. [ABSTRACT FROM AUTHOR]