Recently, perovskite solar cells have attracted great attention because of their outstanding photovoltaic performance and ease of fabrication. High-quality perovskite films hold a key in getting ...highly efficient perovskite solar cells. Solution-processed fabrication technique is the most widely adopted for preparing perovskite films because of its low cost. In the solution-proceed perovskite films, solvents not only play the role of dissolving the solute but also participate in the crystallization of perovskite. In the one-step method, solvents play key roles in controlling morphology, widening process window, and achieving room-temperature crystallization of perovskite films. In addition, the solvents play important roles in controlling the nuclei/growth, suppressing volume expansion during the two-step method. Especially, the solvent can induce grain coarsening during the annealing process. A deep understanding of the multiplicity of roles during the formation of perovskite films will help understand the formation mechanism of perovskite films. Here, a systematic review on the progress in fabrication of high-quality perovskite films by making use of solvent to control the crystallization is presented. Meanwhile, we elucidate the key roles of solvent in the fabrication of high-quality perovskite films.
Excellent high-temperature mechanical properties and high recrystallization temperature are crucial for molybdenum (Mo) alloys in practical applications. The microstructure and high-temperature ...mechanical properties of Mo-0.8%La2O3-2%ZrC alloys prepared by traditional powder metallurgy technology associated with cross rolling post treatment were investigated. Results showed that the Mo1950-rolled alloys had a fine grain size of about 1.65 μm due to hot cross rolling and high tensile strengths of 988 MPa and 189 MPa at room temperature and 1400 °C, respectively. SEM and TEM examinations indicated that although most of the large La2O3 and ZrC particles were distributed along the grain boundaries, some nano-sized particles were well dispersed in intragranular zones. Particularly, dislocations were found to intercepted by the second phase particles in tensile samples, which could effectively enhance both the tensile strength and recrystallization temperature. Dislocation, grain refining, and second phase particles were all found to play important roles in strengthening the alloys below the recrystallization temperature, while second phase particle strengthening was the only strengthening mechanisms above the recrystallization temperature.
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•Mo-La2O3-ZrC alloys were prepared by powder metallurgy and cross rolling process.•The density of the alloys was increased and the crystalline grains were refined.•Tensile strengths were 988 MPa and 124 MPa at room temperature and 1600 °C.•Three typical strengthening mechanisms play synergistical roles at room temperature.•Second phase particle strengthening was the only reinforcing mechanism above 1400 °C.
Tandem solar cells usually use a wide band gap absorber for top cell. The band gap of CuIn
Ga
Se
can be changed from 1.04 eV to 1.68 eV with the ratio of Ga/(In+Ga) from 0 to 1. When the ratio of ...Ga/(In+Ga) is over 0.7, the band gap of CIGS absorber is over 1.48 eV. CIGS absorber with a high Ga content is a possible candidate one for the top cell. In this work, CuInGa precursors were prepared by magnetron sputtering with CuIn and CuGa targets, and CIGS absorbers were prepared by selenization annealing. The Ga/(In+Ga) is changed by changing the thickness of CuIn and CuGa layers. Additionally, CIGS solar cells were prepared using CdS buffer layer. The effects of Ga content on CIGS thin film and CIGS solar cell were studied. The band gap was measured by PL and EQE. The results show that using structure of CuIn/CuGa precursors can make the band gap of CIGS present a gradient band gap, which can obtain a high open circuit voltage and high short circuit current of the device. With the decrease in Ga content, the efficiency of the solar cell increases gradually. Additionally, the highest efficiency of the CIGS solar cells is 11.58% when the ratio of Ga/(In+Ga) is 0.72. The value of Voc is 702 mV. CIGS with high Ga content shows a great potential for the top cell of the tandem solar cell.
Organic-inorganic halide perovskites possess excellent chemical, optical, and electronic properties that make them attractive for next-generation solar cells. In this paper, we introduce ...all-low-temperature processed perovskite solar cells using metal sulfide as an electron transport layer. First, we evaluated the alignment of energy levels at the perovskite/metal sulfide layer interface. The properties of metal sulfide and the perovskite layer, as well as the corresponding device performance, were then investigated. Using a CdS layer as an electron transport layer, we have achieved a maximum power conversion efficiency of 11.2% under reverse scans. The successful use of the CdS layer in perovskite solar cells likely would create new pathways and opportunities for the advancement of device design.
We directly configured double-walled carbon nanotubes as energy conversion materials to fabricate thin-film solar cells, with nanotubes serving as both photogeneration sites and a charge carriers ...collecting/transport layer. The solar cells consist of a semitransparent thin film of nanotubes conformally coated on a n-type crystalline silicon substrate to create high-density p−n heterojunctions between nanotubes and n-Si to favor charge separation and extract electrons (through n-Si) and holes (through nanotubes). Initial tests have shown a power conversion efficiency of >1%, proving that DWNTs-on-Si is a potentially suitable configuration for making solar cells. Our devices are distinct from previously reported organic solar cells based on blends of polymers and nanomaterials, where conjugate polymers generate excitons and nanotubes only serve as a transport path.
•Sb2S3 thin films are grown by vulcanizing evaporated metallic Sb precursor.•Metallic Sb layer cannot be sulfured completely at annealing temperature of 320°C.•Amounts of Sb2S3 loss occur at ...annealing temperature beyond 450°C.•The devices with film annealed at 400°C exhibits the best performance.
In this study, antimony sulfide (Sb2S3) thin films had been grown on Mo-coated glass substrate by evaporating metallic Sb film and subsequent annealing in nitrogen/sulfur (N2/H2S) environment. The effects of annealing temperature on phases, morphologies and compositions of thin films and corresponding devices were investigated. It was found that the metallic Sb layer cannot be sulfured completely at annealing temperature of 320°C, while amount of the formed Sb2S3 loss occured at annealing temperature beyond 450°C. The devices with absorber annealed at 400°C exhibited the best performance as the film possessed improved morphology and phase structure. This study provides new approach to fabricate Sb2S3 thin film and possibilities for large scale industrial application of Sb2S3 thin film solar cells.
•MoSi2/SiC–Mo2C gradient coating on Mo was in situ synthesized in a simple process.•The MoSi2/SiC–Mo2C coating had excellent oxidation resistance at 1600°C in air.•SiC could modulate the thermal ...expansion mismatch between MoSi2 and Mo.•The Mo2C layer could act as a diffusion barrier of Si and C toward Mo substrate.
MoSi2/SiC–Mo2C gradient coating on molybdenum was in situ prepared with pack cementation process by two steps: (1) carburizing with graphite powder to obtain a Mo2C layer on Mo substrate, and (2) siliconizing with Si powder to get a composite MoSi2/SiC layer on the upper part of Mo2C layer. The microstructure and elemental distribution in the coating were investigated with scanning electron microscopy (SEM), back scattered electron (BSE), energy dispersive spectroscopy (EDS), electron probe microanalysis (EPMA) and X-ray diffraction (XRD). Cyclic oxidation tests (at 500°C, 1200°C, 1400°C and 1600°C) demonstrated excellent oxidation resistance for the gradient composite coating and the mass loss was only 0.23% in 60min at 1600°C. XRD, EPMA, thermal dynamic and phase diagram analyses indicated that the Mo2C barrier layer played the key role in slowing down the diffusion of C and Si toward inner Mo substrate at high temperature and principally this contributed to the excellent anti-oxidation for Mo besides the outer MoSi2/SiC composite layer.
One common characteristic of neurodegenerative diseases is dysregulation of iron, usually with observed increases in its concentration in various regions. Heavy alcohol consumption is believed to ...contribute to such iron dysregulation in the brain with accompanying dementia. To examine this effect and related genetic-based individual differences in an animal model, we subjected female mice from 12 BXD recombinant inbred strains to 16 weeks of alcohol consumption using the drinking in the dark (DID) method. Daily consumption was recorded and at the end of 16 weeks hippocampus tissues harvested. Concentrations of iron, copper and zinc were measured using X-ray fluorescence technology. The results showed that, DID increased iron overall across all strains, ranging from 3 to 68%. Copper and Zinc both decreased, ranging from 0.4–42 and 5–35% respectively. Analysis of variance revealed significant strain by treatment interactions for all three metals. Additionally, in the DID group, we observed strain differences in reduction of hippocampus mass. These findings are particularly interesting to us because high alcohol consumption in humans has been associated with neurodegeneration and dementia related to disruption of iron regulation. The findings of alcohol consumption associated decreases in copper and zinc are novel. The role of copper regulation and neurological function related to alcohol consumption is as yet largely unexplored. The role of zinc is better known as a neuromodulator in the hippocampus and appears to be protective against neurological damage. It would seem then, that the alcohol-related decrease in zinc in the hippocampus would be of concern and warrants further study.
Cu2ZnSnS4 (CZTS) films were fabricated from a ceramic quaternary target, through middle frequency magnetron sputtering. A post sulfurization process was applied for the sputtered films and ...sulfurization temperatures ranging from 460 °C to 580 °C were utilized. It has been found that obvious Zn loss exists during the sputtering, making the sputtered films become Zn poor although the target is Zn rich. The sputtered films were not totally amorphous, but composed of small CZTS grains at the size of several nanometers. After a post sulfurization process the crystallinity were greatly improved and films composed of densely packed CZTS grains at the size of several hundred nanometers can be obtained at sulfurization temperatures higher than 520 °C. Yet minor SnS coexists with CZTS since the films were Zn poor and Sn rich. And finally the CZTS films sulfurized at 580 °C depict an optical band gap of around 1.55 eV.
•A ceramic quaternary target was used for Cu2ZnSnS4 fabrication.•Obvious Zn loss exists during the sputtering.•CZTS films with optical band gap of around 1.55 eV can be finally obtained.
•The absorbers of submicron-thick Cu(In,Ga)Se2 solar cells were fabricated by sputtering In2Se3, CuGaSe2 and Cu2Se targets.•The content of Ga in the submicron-thick Cu(In,Ga)Se2 absorbers has been ...optimized.•The highest cells efficiency is 10.3%.
We reported a new method to fabricate submicron-thick CIGS with smooth surface by sputtering In2Se3, CuGaSe2 and Cu2Se targets with post-selenization. The influence of gallium content on the properties of CIGS thin film was evaluated by the crystallinity and the cells performance. The most suitable value of Ga content in our submicron-thick CIGS is 0.32 and cells based on it demonstrated the highest efficiency of 10.3%.
