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The interaction between $$ \{ 10\bar{1}2\} $$ twinning and the LPSO phase was explored in the microstructure of a hot-rolled Mg-5.5Gd-4.4Y-1.1Zn-0.5Zr (wt pct) sheet. The twinning behavior in the nanoscale matrix lamellae, which were sandwiched between LPSO plates, was analyzed using high-resolution transmission electron microscopy. Profuse $$ \{ 10\bar{1}2\} $$ twinning is activated within grains containing the LPSO phase. Twinning easily occurs in the matrix with sparsely distributed LPSO plates, and the twins continually “traverse” across multiple LPSO plates. The occurrence of $$ \{ 10\bar{1}2\} $$ twinning in the matrix lamellae sandwiched between LPSO plates has a significant nanosize effect. With the decrease of matrix lamellae thickness, the nucleation and growth of twins become more difficult. Non-twinned matrix lamellae are found when the lamellae thickness is smaller than 50 nm. Additionally, the LPSO plates, which have been engulfed by twins, exist stably inside the twin after 10 pct hot rolling reduction at the temperature of 450 °C, and decompose during the annealing process. For the multi-pass hot rolling, the decomposition of the LPSO plates during intermediate annealing is considered to be beneficial for the continuous twin growth in the subsequent rolling pass, due to the relaxation of back-stress.

The orientation-dependent deformation mechanisms including $$ \{ 10\bar{1}2\} $$ twinning, prismatic 〈a〉 slip and kink in hot rolling of a Mg-5.5Gd-4.4Y-1.1Zn-0.5Zr (wt pct) alloy containing long-period stacking ordered (LPSO) phases were examined in this study. For grains with c-axes close to the rolling direction, $$ \{ 10\bar{1}2\} $$ twinning is the major deformation mode. As for grains with c-axes close to the transverse direction, prismatic 〈a〉 slip and kink dominate the plastic deformation. Kink serves as a supplementary of prismatic 〈a〉 slip and only appears at a larger rolling reduction. The close value of CRSS for prismatic 〈a〉 slip and $$ \{ 10\bar{1}2\} $$ twinning was identified to be the cause of the competitive relationship between the two deformation modes at the temperature of 450 °C. The influence of LPSO phases on twinning was further evaluated by TEM. Twinning generally occurs in the lamellar matrix between LPSO phases with thickness above 100 nm and vanishes in the lamella with a very small thickness, such as 42 nm. Therefore, the occurrence of twinning is dependent on the thickness of the lamellar matrix between adjacent LPSO phases. As the distribution of LPSO phases in the tested material is relatively sparse, the activation of $$ \{ 10\bar{1}2\} $$ twinning deformation cannot be suppressed effectively.

The effect of grain size on micro-void evolution and further macroscopic fracture in an austenite steel 316LN was studied through a series of experiments together with the full-field crystal plasticity finite element method (CPFEM) simulations. To probe the grain size effect on void behaviors, macroscopic tensile tests and microscopic fractography characterizations were conducted for samples with different grain sizes. A hierarchy modeling approach based on CPFEM was adopted to quantify the gran size effect accordingly. Authentic boundary conditions were enforced on the high-resolved representative volume elements (RVEs) with realistic grain structures and voids. The simulation results demonstrate that the deformation heterogeneity and the scatter of void growth increase with grain size. Via the quantitative analysis of the void dimension, an extended void growth model involving the effect of grain size was proposed on the basis of the Rice and Tracey model. The extended model adopts the Gaussian distribution to describe the non-uniform void growth induced by the grain-scale deformation heterogeneity and manifests the increase of void size deviation with grain size. The variation of void growth with grain size further leads to a transition of fracture modes. For the fine grain sample, coalescence of densely distributed voids dominates the fracture initiation, and the total void volume fraction thus plays a key role; For the coarse grain sample, however, the growth and coalescence of individual large void are critical for fracture occurrence. With the grain size affected void behavior, the ductility of the material is also shown to be grain size dependent. This study thus advances the comprehensive understanding of the micro-mechanics of ductile fracture and the relationship between microstructure and the macroscopic fracture behavior.

The efficiency improvements of large area (244.34 cm2) crystalline silicon solar cells have been receiving significant attention, especially in high-efficiency multi-crystalline silicon (mc-Si) Passivated Emitter and Rear Contact (PERC) cells. The large area boron-doped mc-Si PERC cells were treated with hydrogenation for a different duration based on high-intensity infrared (HI-IR) LEDs of 940 nm. Compared to the boron-doped monocrystalline silicon (mono-Si) PERC cells, different trends of efficiency improvement were displayed after various hydrogenation duration. The results showed that the amplitude of the efficiency improvement was enhanced to the maximum around 8 min but then slowly decreased with the increasing hydrogenation duration. Moreover, we found that the iron-boron (Fe-B) pairs may occupy the dominant role in hindering the improvement of efficiency and the light-induced degradation (LID) after hydrogenation. The trend of efficiency improvement depended on the density of interstitial iron ions (Fe i + ) and the formation and dissociation of Fe-B pairs. Therefore, a longer duration of hydrogenation was required for mc-Si PERC cells than for mono-Si PERC cells to enhance the efficiency and suppress the degradation. Additionally, the duration of hydrogenation was significantly shortened to 1 min when the pre-LID was applied, then the appropriate extension of the hydrogenation duration was more conducive to the efficiency improvement of mc-Si PERC cells.

The hot deformation and dynamic recrystallization (DRX) behaviors of the homogenized Mg-5.6Gd-0.8Zn (wt.%) alloy with high density lamellar long period stacking ordered (LPSO) phases were investigated. The hot compression tests were conducted at temperatures ( T ) ranging from 350 °C to 500 °C and strain rates ( e ˙ ) ranging from 0.001 s to 1 to 1 s-1, by which the hot deformation behavior was characterized by true stress-strain curve and the constitutive equation was calculated. Except for the deformation conditions of T = 350 °C and e ˙ = 0.1–1 s-1, the true stress-strain curves show DRX characteristics. The LPSO phases had inserted great influences on the deformation and DRX mechanisms of the alloy: (i) when deformed at T = 350–450 °C, the LPSO phases had good thermal stability while both twinning and kinking played an important role under various strain rates. The degree of DRX was low and DRXed grains were small. (ii) When deformed at T = 500 °C, the LPSO phases were almost melted into the matrix and slip played a dominant role while the degree of DRX was high and its grains were significantly grown.

Adiabatic shear deformation behaviors in cold-rolled copper under different impact loading directions were systemically investigated in this paper. Split Hopkinson Pressure Bar (SHPB) system was used for the dynamic test. The microstructure and microtexture of the received shear localization regions were investigated by optical microscopy (OM), electron backscatter diffraction (EBSD) technique and microhardness tests. Three hat-shaped specimens were cut from cold-rolled copper sheet with the direction with an angle of 0° (RD sample), 45° (RD-45° sample) and 90° (TD sample) from the rolling direction within the rolling plane. The stress-strain curves indicate that the mechanical properties of the cold-rolled copper sheet show regularity in the work hardening dominated stage and that the shear stress of TD sample is the highest in that of the those three. OM results show that the morphology of adiabatic shear band in three samples shows differences that their deformation processes fall into two categories, pure relative shearing in RD sample and relative shearing with rotation in RD-45° and TD sample. EBSD results reveal that ultrafine grains with high-angle-boundaries are found within the adiabatic shear bands in three samples. The microhardness measurements show that the microhardness of shear region in three samples are significant higher than that of other regions. However, the size of grains within the shear band in RD sample are much larger than that in the other two samples. Microtexture analysis reveals that the grain orientations inside the shear band in three samples show similar characteristics that the direction tends to parallel to the local shear direction and the {111} and {100} planes tend to parallel to the local shear plane. The calculated results show that rotational dynamic recrystallization can take place in the shear band.

Mg-6.75Zn-0.57Zr-0.4Y-0.18Gd (wt.%) sheet with typical basal texture was produced by cross rolling and annealing. Room temperature tensile tests were subsequently conducted along rolling direction (RD), transverse direction (TD), and diagonal direction (RD45). Deformation mechanism and orientation evolution during the tension were investigated by quasi-in-situ electron backscatter diffraction observation and in-grain misorientation axis analysis. The results indicate that the activation of deformation mechanism mainly depends on the initial grain orientation. For RD sample, prismatic 〈a〉 slip plays an important role in the deformation of grains with 〈0001〉 axis nearly perpendicular to the RD. With the 〈0001〉 axis gradually tilted towards the RD, basal 〈a〉 slip becomes the dominant deformation mode. After the tensile fracture, the initial concentrically distributed {0001} pole is split into double peaks extending perpendicular to the RD, and the randomly distributed { 10 1 ¯ 0 } pole becomes parallel to the RD. The evolution in {0001} and { 10 1 ¯ 0 } poles during tension is related to the lattice rotation induced by basal 〈a〉 slip and prismatic 〈a〉 slip, respectively. TD and RD45 samples exhibit similar deformation mechanism and orientation evolution as the RD sample, which results in the nearly isotropic mechanical properties in the annealed cross-rolled sheet.

This paper presents an ultra-wideband high-gain antenna-in-package, operating at millimeter-wave frequencies, featuring two identical radiating patches, two embedded feeding structures, and a coplanar open-cavity. The feeding structures and the cavity are constructed with metallic vias embedded in the substrate for impedance and gain bandwidth enhancing purposes. Two additional structural modifications, involving 12 shorting vias and a rectangular ring strip, are used to further improve the antenna’s impedance and gain bandwidths. The new antenna design yields a 96.5% and 83.25% of impedance and gain bandwidths, in which $S_{11} \lt-10dB$ and gain >9dBi, respectively. In addition, the antenna is light, compact, and easy to be integrated with planar circuits because all the structures are implemented with planar fabrication technologies, such as LTCC and HDI processes.

Although the monocrystalline silicon (mono-Si)-passivated emitter and rear contact (PERC) solar cells have achieved incredible efficiency, they still can be further improved by hydrogenation. So the hydrogenation was performed to investigate the improvement of large area (>240 cm2) mono-Si PERC solar cells and estimate the significance of previous light-induced degradation (pre-LID) under a high-intensity infrared (HI-IR) LEDs source platform. Then, the results indicated that the parameters, such as open-circuit voltage (Uoc) and short-circuit current density (Jsc) and fill factor (FF), could be better improved after LED hydrogenation with the execution of the pre-LID. The efficiency of mono-Si PERC solar cells with pre-LID increased by ~0.190 ± 0.005%abs. for 2 min, which was higher than that without pre-LID (0.115 ± 0.005%abs.). Moreover, the results showed that the efficiency of large area mono-Si PERC solar cells with light-induced degradation (LID) treatment after LED hydrogenation only existed a slight degradation of about −0.253 ± 0.005%rel.. Compared with mono-Si PERC solar cells without pre-LID, the efficiency improvement and LID mitigation of mono-Si solar cells with pre-LID was faster and more significant by LED hydrogenation, so that the LED hydrogenation time significantly can shorten from 6 to 2 min. Additionally, the possible presence of a boron-oxygen (BO) model was estimated, and this BO model is susceptible to be activated by the injection of external energy, resulting in more BO defects in the process of pre-LID, so that subsequent hydrogenation rate becomes faster.

Anisotropy photoresponse can be effectively achieved based on gradient organic heterojunction. However, the gradient heterojunction has yet been studied due to the complicated process and great random error inside. Especially in the field of transient optics, the light on/off in femto/picosecond range is vitally important for high-speed optical systems, such as application in fiber communications. In this paper, the wedge-structured organic heterojunction was fabricated based on molecular beam epitaxy. The devices were combined with both wedge-structured heterojunction and half-wave plate. When the probe light was tuned to 2.0 eV, a narrow passband was instantly observed once the pump and probe light were perpendicular to each other. The photoresponse can be achieved within 0.84 ps which can tune the optical signals on and off in transient optics. The results have demonstrated an exciting application in photo sensing.

In this work, deformation behavior of an extruded Mg-Zn-Gd-Y-Zr alloy sheet, including mechanical anisotropy and tension-compression asymmetry, were investigated by conducting tension and compression experiments along different directions. Coupling with the strong texture, the role of long-period stacking ordered (LPSO) phases in the deformation behavior was analyzed based on the microscopic plastic deformation theory. The results showed that LPSO phases with different morphologies played different roles in deformation behavior of the strong textured Mg-Zn-Gd-Y-Zr alloy sheet: (i) the irregular-shaped LPSO phases distributed along extrusion direction (ED) brought anisotropic fiber reinforcement and exacerbated the mechanical anisotropy; (ii) the needle-like LPSO phases filled in the grain interior hindered the propagation of twinning boundaries and decreased the tension-compression asymmetry. The results may provide valuable references for the manufacturing of large size Mg/LPSO alloys with low mechanical anisotropy and tension-compression asymmetry, hence making them better to meet the growing need of engineering application.

In this paper, we have found that the efficiency of p-type mono-crystalline silicon (mono-Si) passivated emitter and rear contact (PERC) solar cells can be increased by $$0.12{\%}_{\mathrm {{abs.}}}$$ with the process of hydrogenation with electron injection (HEI). However, the same scheme was not suitable for p-type multi-crystalline silicon (mc-Si) solar cells. To promote power conversion efficiency (PCE) for the mc-Si solar cells, we have explored a developed HEI process for the mc-Si solar cells to improve the device performance. Meanwhile, we also analysed the mechanization inside the solar cells after applying the HEI process. Through the design of experiment (DOE), the correlation among injection current, temperature, injection time and efficiency improvement was analysed in detail. It was proved that mc-Si solar cells require higher current injection and temperature to passivate the complex impurities in the bulk, when compared to mono-Si solar cells. With the optimal scheme explored by this paper, the open circuit voltage ( $$U_{\mathrm {{oc}}}$$ ), short circuit current density ( $$J_{\mathrm {{sc}}}$$ ) and fill factor (FF) of p-type mc-Si solar cells, respectively, increased by 1.2 mV, 0.11 mA $$\hbox {cm}^{-\mathrm {{2}}}$$ and $$0.05{\%}_{\mathrm {{abs.}}}$$ , respectively. The efficiency was improved about $$0.11 \pm 0.005{\%}_{\mathrm {{abs.}}}$$ . These results will provide a certain method and basis for further improving the efficiency of mc-Si PERC cells and overcoming the light-elevated temperature-induced degradation by HEI process.

A large size Mg-1.2Zn-3.4Y-4.7Gd-0.5Zr (wt%) alloy sheet was manufactured by semi-continuous casting, homogenization and hot extrusion, in which the microstructures were systematically examined. The results showed that: (i) During homogenization, the generation of 14H LPSO phase was mainly achieved by two phase transition processes of “Mg5(Gd,Y,Zn) phase → 14H LPSO phase” and “18R LPSO phase → 14H LPSO phase”. (ii) During extrusion, the evolution of LPSO phases with various morphologies was driven by severe deformation and dynamic recrystallization (DRX). Under severe deformation, the 14H LPSO phases in homogenized alloy were broken down to fragments with various sizes. Under the influence of DRX, the deformation defects of small LPSO fragments were fully eliminated and formed the “sandwich-like” LPSO phase. While the deformation defects of coarse LPSO fragments were less eliminated and formed the “irregular-shaped” LPSO phase. Meanwhile, due to the decreased solubility of Zn, Y and Gd in the extruded alloy matrix, the solution elements of Zn, Y and Gd were impelled to precipitate at the scattering arranged stacking faults (SFs) and formed the “needle-like” LPSO phase. It is found that the gliding of Shockley partial dislocation(s) on basal plane was structurally needed during the precipitation of needle-like LPSO phase. Keywords: Magnesium alloy, LPSO phase, Stacking faults, Extrusion, Recrystallization (DRX)

The texture evolution, crystal orientation-dependent deformation mechanism and mechanical properties of the Mg-5.5Gd-4.4Y-1.1Zn-0.5Zr (wt%) alloy sheet with bimodal grain structure during hot rolling were investigated in this study. The pre-rolled sheet possesses the texture with c-axis randomly distributed in rolling-transverse plane. During the hot rolling deformation, the initial texture is gradually changed to an uncommon texture with c-axis continuously distributed between transverse direction (TD) and normal direction (ND) of the rolled sheet. The formation of the texture is related to the orientation-dependent deformation mechanism of coarse grains. For the coarse grains with c-axis close to rolling direction (RD), {10-12} twinning was identified to be the dominated deformation mechanism. With the activation of twinning, the c-axis of the matrix is reoriented towards ND. For the coarse grains with c-axis near TD, prism slip and kink deformation were figured out as the dominated deformation modes. In early stage of the hot rolling deformation, the c-axis of the grains remains in TD with the activation of prism slip. Afterwards, kink deformation activates and the c-axis of the grains is rotated away from TD towards ND with different degrees. In addition, the mechanical properties of rolled sheets were examined and the results demonstrate that yield strength and tensile strength are gradually improved by rolling deformation. Nevertheless, the improvement of yield strength in RD is much greater than that in TD and a serious yield strength anisotropy is shown in the rolled sheet. The strong yield strength anisotropy derives from the variation of texture strengthening in the RD and TD due to the formation the texture with c-axis continuously distributed between TD and ND.

The mechanical behavior and microstructure characteristics of Ti-5Mo-5V-8Cr-3Al alloy were investigated with hat-shaped samples compressed under quasi-static and dynamic loading. Compared with the quasi-static loading, a higher shear stress peak and a shear instability stage were observed during the dynamic shear response. The results showed that an adiabatic shear band consisting of ultrafine equiaxed grains was only developed in the dynamic specimen, while a wider shear region was formed in the quasi-static specimen. The microhardness measurements revealed that shear region in the quasi-static specimen and adiabatic shear band in the dynamic specimen exhibited higher hardness than that of adjacent regions due to the strain hardening and grain refining, respectively. A stable orientation, in which the crystallographic {110} planes and directions were respectively parallel to the shear plane and shear direction, developed in both specimens. And the microtexture of the adiabatic shear band was more well-defined than that of the shear region in the quasi-static specimen. Rotational dynamic recrystallization mechanism was suggested to explain the formation of ultrafine equiaxed grains within the adiabatic shear band by thermodynamic and kinetic calculations.

The tensile deformation behavior and corresponding microstructure evolution of the Mg-4.7Gd-3.4Y-1.2Zn-0.5Zr (at. %) magnesium alloy with long period stacking structure (LPSO) are studied by electron backscatter diffraction (EBSD) and slip lines methods. The results show that less and very small size of twins is observed in the grains with high value of Schmid factor for twinning, which indicates that the growth of the {10–12} twinning deformation is prevented by the LPSO phase. The prismatic lines present in grains of which the prismatic slip Schmid factor is above 0.4. The favorable orientation and LPSO phase synergistically promote the activation of prismatic slip. The inhomogeneous rotation of the grains during deformation is the reason for the microcrack at grain boundary.

Microstructure and mechanical properties of the Mg-6.75%Zn-0.57%Zr-0.4%Y-0.18%Gd sheets processed by unidirectional and cross rolling were investigated. Compared with the unidirectional rolling (UR) sheet, cross rolling (CR) sheet exhibits finer grain size, weaker basal texture, higher recrystallized volume fraction and higher strength. Meanwhile, the UR sheet shows strong mechanical anisotropy, while the approximate mechanical isotropy is successfully achieved in the CR sheet. Cross rolling effectively reduced the anisotropy of mechanical properties. The finer grains in the CR sheet are responsible to its higher yield strength. The anisotropy of yield strength results from the basal slip, while the activation of prismatic slip reduced this anisotropy. The recrystallized components in the CR sheet weaken basal texture, thereby reducing anisotropy.

Light injection and cooling conditions can induce some differences in the temperature-raising time of multi-crystalline silicon (mc-Si) solar cells. Through real-time tracking and monitoring of sample surface temperature, the temperature-raising steps for achieving the optimum efficiency improvement and degradation mitigation were optimized and modified. Then the corresponding hydrogenation treatments under a high-intensity infrared LEDs source were carried out based on improved steps. The results indicated that the optimal temperature-raising time should be manipulated at around 60 s and then followed by a 2-min hydrogenation treatment. Furthermore, the temperature-raising process should keep the temperature rising continuously without interruption or temperature drop. However, excessive thermal treatment time damaged the formation of defect precursors and extended the hydrogenation time. Moreover, the Fourier Transform Infrared spectrum curves illustrated that the peak intensity of the Si–H bonds treated at the 60-s temperature-raising time was more significant than that of other temperature-raising time treatments.

P-type multi-crystal (mc-Si) solar cells are facing relative weaker competitiveness compared to mono-crystal silicon solar cells due to the efficiency improvement bottleneck. To further enhance the efficiency of p-type mc-Si solar cells, we have systematically investigated the technology of hydrogenation with electron injection (HEI) on p-type mc-Si solar cells with different power conversion efficiency (PCE) grades. Experimental results manifested that the efficiency promotion of cells with higher efficiency (HE) was lower compared to that of lower efficiency (LE) cells under the same HEI processing condition, whether for conventional or passivated emitter and rear cells. Further investigations were carried out to prove that the effectiveness of HEI treatment was closely related to the concentration of both available hydrogen and defect in the bulk of solar cells. This highlighted that the lower concentration of available hydrogen was more helpful for HE cells to improve the electrical performances, which was contrary to LE cells due to the different distribution of defects in the bulk. Besides, programing analysis was implemented to optimize the HEI treatment scheme of HE cells, and the PCE was finally improved by 0.63%rel. ± 0.05%. This result provided an improved technological process to further improve the efficiency gains in the production process, where a classification method was introduced according to the efficiency distribution before HEI treatment. The proposed method can distribute solar cells into appropriate grades to avoid wasting resources in mass production.

Precipitate strengthening against {10 1 ¯ 2} twinning was examined and compared with basal and prismatic slip in a strongly textured Mg 9Al extrusion plate. The plate was aged for various periods of time and mechanically tested in three orientations. The estimated critical resolved shear stresses (CRSS) for {10 1 ¯ 2} twinning was increased by 54 MPa, significantly larger than the 18 MPa for basal and the 21 MPa for prismatic slip. Of the two types of precipitate responsible for the larger increment of CRSS for twinning, the discontinuous precipitate was suggested to have a stronger suppressing effect on the twin nucleation and propagation than the continuous precipitate.

In this study, the extruded Mg-6.9Gd-3.2Y-1.5Zn-0.5Zr (wt%) alloy was annealed at 693 K for 1–120 h, evolution of the long-period stacking ordered (LPSO) phases under elevated temperature and their effect on the recrystallization behavior were investigated. Initial microstructure of the extruded alloy consists of coarse deformed grains containing thin plate-shaped 14H-LPSO phase and fine recrystallized grains containing lamellar metastable phase. During annealing, deformed grains are gradually consumed by growing recrystallized grains, accompanied by dissolution of the LPSO phase in the former. Meanwhile, lamellar metastable phase within recrystallized grains transforms into thin plate-shaped 14H-LPSO phase, and simultaneously grows along the basal plane and thickens along the c-axis direction. Migration of recrystallized grain boundary is hindered by the LPSO phase in deformed grains. The hindrance is more significant along the c-axis of LPSO phase due to the remaining Mg matrix between LPSO phase and recrystallized grain boundary. While parallel to the basal plane of LPSO phase, the LPSO phase directly contacts recrystallized grain boundary, and the hindrance is weakened. Besides, the LPSO phase formed in recrystallized grains can also restrict the migration of grain boundary.

In this study, multi-directional forging (MDF) experiments were conducted to a homogenized Mg-2.36Y-0.98Zn (at%) alloy containing long period stacking ordered (LPSO) phase. Microstructure evolution of the MDFed alloys with different forging passes were systematically investigated, corresponding microhardness development was also concerned. The results revealed that grain refinement, texture weakening and DRX development during MDF were closely relevant to fragmentation of LPSO phase. It was also found that development of average microhardness and mechanical heterogeneity of the MDFed alloys can be attributed to the competition and balance of work hardening, grain refinement and DRX softening. Furthermore, LPSO-related deformation and dynamic recrystallization (DRX) behaviors such as (i) kink-aided DRX (KDRX, this concept was firstly nominated in this study); (ii) particle stimulated nucleation mechanism (PSN) and (iii) pinning effect on DRX nucleus were thoroughly discussed, which should help to understand the unique microstructure evolution of LPSO-containing Mg alloys, and thus offer certain enlightenment for manufacturing LPSO-strengthened Mg alloys with excellent mechanical property.

Perovskite Solar Cells (PSCs) have drawn tremendous attentions from scientific community due to their advantages of high efficiency and low-cost. However, the mechanism of photoelectron generation is unclear because the light field distribution is difficult to be quantitively characterized by conventional methods. The Optical Transfer Matrix Method (OTMM) has been applied in organic devices based on p-n structures. We have applied different materials as back electrode to examine the light propagation inside of planar p-i-n solar cells with regular structure (Glass/ITO/SnOx/CH3NH3PbI3/Spiro-OMeTAD/Back electrode). The simulations were performed by using OTMM to carry out the optical field modeling of simulated solar cells in visible-near infrared (NIR) range. Among the simulation models, it has been found that perovskite solar cells based on sliver electrode has highest light intensity oscillation and faster charge generation rate. But sliver electrode has lower stability because the iodine can diffuse to the interface and form AgI with the assist of NIR-induced thermal effect. By contrast, the independent graphene electrode has disadvantages of interlayer conductivity and transparency. Based on the simulation result, we recommend that the graphene can be applied as a buffer layer between perovskite and sliver electrode instead of being an independent electrode.

A Mg–Zn–Y alloy containing long period stacking ordered (LPSO) phases was compressed at temperatures ranging from 623 K to 773 K and strain rates ranging from 0.001 s−1 to 1 s−1. The role of LPSO phase in dynamic recrystallization (DRX) was emphatically studied. The results revealed that: (i) the area filled with kinked LPSO phase is found as potential site favors the initiation of DRX at lower temperatures. (ii) Fragmentation of LPSO phase at initial grain boundaries significantly improves the DRX process via particle stimulated nucleation (PSN) mechanism. (iii) Boundary migration of DRX grains is frequently pinned by LPSO phase at elevated temperature. Understanding the role of LPSO phase in DRX may shed light on manufacturing of Mg–Zn–RE alloys with excellent mechanical property and good corrosion resistance.

Two interaction modes between kinking and { 10 1 ‾ 2 } twinning in a Mg–Zn-Gd alloy containing long period stacking ordered (LPSO) phase are thoroughly investigated: (i) when kinking forms prior to twinning, twins concomitantly nuclear at kink boundaries (KBs) and twinning propagation is frequently restricted by two adjacent KBs. By contrast, (ii) when twinning forms prior to kinking, kink deformation locally breaks the twins’ theoretical misorientation to their adjacent matrixes, during which basal slip plays a vital role in accommodating the asynchronous deformation between kinking and twinning.

The research on the hydrogen passivation process for silicon solar cells has been developed for a long time. Recently, researchers have investigated the use of lasers as light sources. It has been found that hydrogen passivation technology can improve the minority carrier lifetime and passivate some impurities and defects in silicon solar cells. In this paper, a hydrogenation platform for silicon solar cells based on high intensity infrared LEDs of 940 nm was built. After a number of comparative experiments, electrical characteristics, photo-luminescence images, and light beam induced current were applied before and after hydrogenation to distinguish the passivation effect. It was found that the effect of hydrogen passivation on monocrystalline boron-doped passivated emitter and rear contact (PERC) solar cells by using infrared LEDs as the light source was satisfactory under the condition of suitable light intensity and temperature. It has a remarkable effect on improving the electrical characteristics an...

With the development of high-efficiency solar cells, the issue of industrial Si photovoltaic (PV) cells' light-induced degradation (LID) became even more serious. In this paper, a method for quick LID treatments was developed. A high-intensity monochromatic light source was used to realize a quick LID treatment, and 940-nm light-emitting diodes (LEDs) were selected to build a high-intensity LID treatment platform. The photon flux density output from this light source can reach 1.32 × 1023 m−2 s−1. From the simulation and calculation, the photons of 1.27× 1023 m−2 s−1 can be utilized by a 200-μm-thick typical Cz Si passivated emitter rear cell (PERC) under the illumination of this light source, whereas only 2.44 × 1021 m−2 s−1 photons can be used under the airmass 1.5 global (AM1.5G) conditions. Only 6 min of irradiation was needed under this monochromatic LED light source to reach the same amount of photons utilized by the cells under the AM1.5G illumination for 5 h. In the actual situation, the temperatu...

For a comprehensive understanding of cells or tissues, it is important to enable multiple studies under the controllable microenvironment of a chip. In this report, we present an integrated microfluidic cell culture platform in which endothelial cells (ECs) are under static conditions or exposed to a pulsatile and oscillatory shear stress. Through the integration of a microgap, self-contained flow loop, pneumatic pumps, and valves, the novel microfluidic chip achieved multiple functions: pulsatile and oscillatory fluid circulation, cell trapping, cell culture, the formation of ECs barrier, and adding shear stress on cells. After being introduced into the chip by gravity, the ECs arranged along the microgap with the help of hydrodynamic forces and grew in the microchannel for more than 7 days. The cells proliferated and migrated to form a barrier at the microgap to mimic the vessel wall, which separated the microenvironment into two compartments, microchannel and microchamber. An optimized pneumatic micropump was embedded to actuate flow circulation in a self-contained loop that induced a pulsatile and oscillatory shear stress at physiological levels on the ECs in the microchannel. All the analyses were performed under either static or dynamic conditions. The performance of the barrier was evaluated by the diffusion and distribution behaviors of fluorescently labeled albumin. The permeability of the barrier was comparable to that in traditional in vitro assays. The concentration gradients of the tracer formed in the microchamber can potentially be used to study cell polarization, migration and communications in the future. Additionally, the morphology and cytoskeleton of the ECs response to the pulsatile and oscillatory shear stress were analyzed. The microfluidic chip provided a multifunctional platform to enable comprehensive studies of blood vessels at the cell or tissue level.

This study reports on the development of a novel perfusion microfluidic cell culture device integrated drug delivering, fluid controlling and cell culturing functions on a two-layer PDMS chip. The device consists of an array of 6×6 cell culture chambers, a drug gradient generator and two control valves. Cells are physically trapped and cultured in the center of the chamber by a C-shaped dam when cells loading. Drug gradient network is able to generate 6 gradient drug concentrations to treat the culture cells. And the hydraulic valves can not only make control of the fluid flow to mimic the microenvironment of cells, but keep different kind of cells separately cultured. We have investigated the effect of the hydraulic valves on fluid control, and the chip's ability to generate a range of chemical gradient concentrations. Three kinds of Human cells (L-02, SMMC-7721 and HUVEC-2C) are grown well after three-day continuous perfusion culturing in the chip. Therefore the microfluidic cell culture device shows the potential to make significant impacts in cell-based research of high throughput drug screening, tissue engineering and clinical medicine.