Reduction of Threading Dislocation Density in Sputtered Ge/Si(100) Epitaxial Films by Continuous-Wave Diode Laser-Induced Recrystallization

We have developed a cost-effective, up-scalable, and high-throughput method combining continuous-wave (CW) diode laser and magnetron sputtering for fabricating low-defect single-crystalline Ge films for high-efficiency III–V solar cell applications. CW diode laser-induced recrystallization is demonstrated to dramatically reduce the threading dislocation density (TDD) of sputter-deposited single-crystalline Ge/Si epitaxial films by more than 3 orders of magnitude. This might be due to the change of growth mechanism from initial Ge/Si heteroepitaxy in the sputtering process to Ge/Ge homoepitaxy by the laser-induced lateral recrystallization process, overcoming the typical issue of Ge/Si lattice mismatch to achieve low TDD

Spatial Grain Growth and Composition Evolution during Sulfurizing Metastable Wurtzite Cu₂ZnSnS₄ Nanocrystal-Based Coatings

A drawback of nanocrystal-based processing, that leads to the notoriously poor crystallinity of pure-sulfide Cu₂ZnSnS₄ absorber, was recently reported to be effectively overcome by the annealing of thin films made from the ink of metastable wurtzite Cu₂ZnSnS₄ nanocrystals in a combined S and SnS atmosphere. However, the formation pathway from nanometer-sized crystals in the wurtzite phase to micrometer-sized grains with the kesterite phase during this process still lacks in-depth study. In this work, the spatial grain growth and composition evolution during the sulfurization of wurtzite nanocrystal coatings are systematically investigated by classifying samples into temperature and time series. In the process of heating up, the reversible migration of Cu and Zn species contributes to a continuous growth of kesterite Cu₂ZnSnS₄ grains on the surface. At higher temperature, a fast phase-transition growth from wurtzite Cu₂ZnSnS₄ nanoparticles to kesterite grains is also directly observed in the region away from the surface. After reaching 580 °C, the thin film experiences impressive decomposition and reorganization changes as a function of time, which cause the formation of an absorber with good crystallinity and homogeneous compositional distribution. The solar cell device, fabricated by employing this pure-sulfide Cu₂ZnSnS₄ absorber from wurtzite nanocrystal-based coatings, demonstrated an energy conversion efficiency of 6.0% in the absence of an antireflection coating

Emerging chalcohalide materials for energy applications

Semiconductors with multiple anions currently provide a new materials platform from which improved functionality emerges, posing new challenges and opportunities in material science. This review has endeavored to emphasize the versatility of the emerging family of semiconductors consisting of mixed chalcogen and halogen anions, known as “chalcohalides”. As they are multifunctional, these materials are of general interest to the wider research community, ranging from theoretical/computational scientists to experimental materials scientists.This review provides a comprehensive overview of the development of emerging Bi- and Sb-based as well as a new Cu, Sn, Pb, Ag, and hybrid organic−inorganic perovskite-based chalcohalides. We first highlight the high-throughput computational techniques to design and develop these chalcohalide materials.We then proceed to discuss their optoelectronic properties,band structures, stability, and structural chemistry employing theoretical and experimental underpinning toward high-performance devices. Next, we present an overview of recent advancements in the synthesis and their wide range of applications in energy conversion and storage devices. Finally, we conclude the review by outlining the impediments and important aspects in this field as well as offering perspectives on future research directions to further promote the development of chalcohalide materials in practical applications in the future.</p

A Green Lead Recycling Strategy from Used Lead Acid Batteries for Efficient Inverted Perovskite Solar Cells

Lead is widely used as a crucial elemental for lead acid batteries (LABs) and emerging halide perovskite solar cells (PSCs). However, the use of soluble lead will raise environmental concerns. For the purpose of Pb recycling, herein, we report a reactant-recycling strategy to extract Pb from used LABs and synthesize high-purity PbI2. The recycled PbI2 shows smaller grain size, higher crystallinity, and higher thermal stability compared to the commercial sources. Perovskite films deposited with the high-quality PbI2 show larger grain size and fewer defects than the commercial ones. Consequently, the synthesized PbI2 enables a power conversation efficiency of 20.45% for the inverted MAPbI3 (MA= methylammonium) PSCs with excellent air stability. This work offers a novel strategy for lead recovery from LABs and a green path for the realization of high-performance PSCs with high defect tolerance

Methylammonium Lead Bromide Perovskite-Based Solar Cells by Vapor-Assisted Deposition

The past two years have seen the uniquely rapid emergence of a new class of solar cell based on organic–inorganic halide perovskite. Although less explored than its tri-iodide counterparts, CH₃NH₃PbBr₃ has a larger bandgap of 2.3 eV with a higher voltage potential that is suitable for tandem solar cell applications. In this paper, we report a vapor-assisted method for depositing and fully crystallizing CH₃NH₃PbBr₃ film on mesoporous TiO₂ with good coverage. CH₃NH₃PbBr₃ fabricated using this method has demonstrated long carrier diffusion length (>1 μm) as estimated by transient photoluminescence-quenching measurements. We demonstrate solar cells fabricated using such films and spiro-OMeTAD as the hole transport layer with an averaged (from forward and reverse scans) conversion efficiency of 8.7%, <i>V</i>_oc of 1.45 V, <i>J</i>_sc of 9.75 mA/cm², and fill factor of 61.5%

Evidence of Low-Temperature Joints in Silver Nanowire Based Transparent Conducting Layers for Solar Cells

The primary stage of joint formation of silver nanowires (AgNWs) at 60 °C is investigated by using rotary scanning transmission electron microscopy (STEM with tomographic reconstruction images) and super-large-scale molecular dynamic (MD) simulation (2 × 106 atoms). This study proves to establish that silver nanowires do not require the conventional high-temperature post-treatment process at 200 °C to form fused contacts at the intersections. In fact, a low-temperature annealing at 60 °C facilitates formation of highly conductive networks. The connection between the nanowires is made through a stage called thinning, shown in this report for the first time, which occurs before broadening of the nanowires and is caused due to simultaneous effects of loads from the top nanowires and the heating, as confirmed by STEM and MD results. The outcomes of our investigation significantly promote the application of AgNWs as a transparent conductive layer for solar cells with requirement of low-temperature processing such as kasterite, perovskite, and organic solar cells

Additional file 1 of Long read sequencing revealed proventricular virome of broiler chicken with transmission viral proventriculitis

Additional file 1. Supplementary figure

Additional file 1 of Serological investigation of Gyrovirus homsa1 infections in chickens in China

Additional file 1

Understanding the Key Factors of Enhancing Phase and Compositional Controllability for 6% Efficient Pure-Sulfide Cu₂ZnSnS₄ Solar Cells Prepared from Quaternary Wurtzite Nanocrystals

Pure-sulfide Cu₂ZnSnS₄ thin film solar cells were fabricated employing a facile and low-cost preparation procedure by depositing wurtzite CZTS nanocrystals, followed by high temperature sulfurization. The exploration of previously reported devices with >4.8% efficiency has demonstrated the potential application of wurtzite nanocrystals in optoelectronic devices. Moreover, TEM-EDS characterization revealed the presence of compositional fluctuations within the fine-grained sublayer that may limit the performance of the final devices. To reduce the fine-grained sublayer and further improve the crystalline quality of the active large-grained layer of our solar cells, the Na doping method and the sulfurization process were both systematically studied in this work. The crystal phase, morphology, elemental composition, and photovoltaic performance were characterized. These results indicate that, for the wurtzite material system, (1) tuning the Na amount is necessary, yet insufficient to ensure the good performance of solar cells and (2) the introduction of SnS powder in the sulfurization treatment provides leverage with which to improve the microstructure and compositional distribution of the final absorber. By employing this leverage to optimize our CZTS absorbers prepared from quaternary wurtzite nanocrystals, the performances of solar cells has been increased to 6.0% in the absence of an antireflection coating

Unraveling the Mechanism of Ion-Migration Suppression by Interstitial Doping for Operationally Stable CsPbI₂Br Perovskite Solar Cells

Despite the remarkable advances of inorganic perovskite solar cells (PSCs) by extrinsic metal doping, the doping mechanism and physical location of doping ions are still ambiguous. Herein, the ion-migration behavior of inorganic PSCs is studied theoretically and experimentally for Sm-doped CsPbI2Br perovskites. The structural characterizations and density functional theory (DFT) calculation confirm the interstitial occupancy of the dopant Sm in the CsPbI2Br perovskite lattice. The ion-migration behavior was systematically unveiled by employing multiple photoelectrochemical techniques. The results show that with Sm interstitial doping in the CsPbI2Br perovskite, the operational stability of PSCs is dramatically improved owing to effectively suppressed ion migration, demonstrated by alleviated VOC change at different scan rates, weaker response to electric poling, faster photocurrent response, higher activation energy of mobile ions, and much more stable maximum power point (MPP) tracking performance. With theoretical model-supported experimental investigation, this research unravels the mechanism of ion-migration suppression in CsPbI2Br PSCs by interstitial doping. This may pave the way to achieve operational stability of PSCs through facile cost-effective practice