Polysilicon Research Articles

Evaluation of Bosch processing and C4F8 plasma deposition at cryogenic temperatures

Abstract The Bosch process was studied at a substrate temperature of −100 °C and compared to etchings performed at room temperature, as in the general case. The tests were realized using an inductively coupled plasma reactor by varying C4F8 passivating gas flow injections both at +20 °C and −100 °C. It was observed that the Bosch process is effectively temperature dependent and that the necessary C4F8 passivating gas flow can be reduced to obtain similar anisotropic profiles at −100 °C compared to the ambient temperature process. For example, in one of the studied cases, a fluorocarbon injection of 8 sccm was sufficient to obtain an anisotropic etch rate of up to 4.4 μm min−1 at −100 °C whereas the profile obtained at +20 °C using the same parameters presents lateral etching defects with a reduced etch rate of 2.4 μm min−1. At this point, the C4F8 flow must be increased to 12 sccm (50% more) to retrieve an anisotropic profile with an etch rate of 4.0 μm min−1. In the case of cryogenic Bosch (cryo-Bosch) processing, C4F8 feed dosing has a greater influence on the passivation regime which affects the subsequent etching result but it can be easily refined through the optimization of process parameters. An in-situ ellipsometry study of the deposition rate of C4F8 on both polycrystalline silicon (p-Si) and SiO2 substrates was realized by varying the gas flow at −100 °C and +20 °C. This study shows that the deposited fluorocarbon material is approximately a hundred times thicker at cryogenic temperatures using the same process parameters. Scanning electron microscopy (SEM) observation of these samples are in adequacy with the ellipsometry results. Cryo–Bosch etching also results in a slightly higher etch rate compared to room temperature processing when analyzing similar anisotropic profiles. Si:SiO2 etching selectivity is significantly increased at −100 °C although the aspect-ratio dependent etching phenomenon is more important.

Optimizing the diamond wire sawing of polycrystalline silicon: An experimental approach

This study aims to determine the optimized cutting conditions for diamond wire sawing of polycrystalline silicon (poly-Si) wafers using a laboratory machine-tool that employs continuous cutting movement and reach cutting conditions similar to those in the industry. The experimental cutting was carried out following a central composite design, varying the wire cutting speed (vc) and feed rate (vf). A response surface methodology was employed to find the optimized cutting conditions for minimum surface roughness and subsurface micro-crack depth of the as-sawn poly-Si wafer. The results showed that the as-sawn poly-Si exhibited ductile scratches and fragile fractures in its surface morphology, with high vc and low vf resulting in a smooth surface. The response surfaces indicated that increasing vf led to increased Ra and Rq values, while increasing vc reduced them. Median micro-cracks were slightly inclined in the subsurface region, with the response surface indicating that their depth reduced with increasing vc and decreasing vf. The vf/vc ratio significantly affected surface integrity, with a lower vf/vc ratio being more suitable for reaching a smoother surface and shallower subsurface damage. The following material removal mechanisms was identified: optimal ductile region, ductile-to-brittle transition, brittle-ductile mixture region, and brittle region. Simulations using the response surface models indicated minimum values of Ra = 0.35 μm, Rq = 0.48 μm and SSD = 3.29 μm. Thus, this study provides a processing parameter window for diamond wire sawing of poly-Si wafers, which could be useful for both the photovoltaic and microelectronic industries.

Enhancing Power and Thermal Gradient of Solar Photovoltaic Panels with Torched Fly-Ash Tiles for Greener Buildings

Solar photovoltaic (PV) panels that use polycrystalline silicon cells are a promising technique for producing renewable energy, although research on the cells’ efficiency and thermal control is still ongoing. This experimental research aims to investigate a novel way to improve power output and thermal performance by combining solar PV panels with burned fly-ash tiles. Made from burning industrial waste, torched fly ash has special qualities that make it useful for architectural applications. These qualities include better thermal insulation, strengthened structural integrity, and high energy efficiency. Our test setup shows that when solar PV panels are combined with torched fly-ash tiles, power generation rises by 7% and surface temperature decreases by 3% when compared to standard panels. The enhanced PV efficiency is ascribed to the outstanding thermal insulation properties of fly ash tiles and their capacity to control panel temperature. To ensure longevity and safety in building applications, the tiles employed in this study had a water absorption rate of 5.37%, flexural strength of 2.95 N/mm2, and slip resistance at 38 km/h. Furthermore, we find improved structural resilience and lower cooling costs when up to 30% of the sand in floor tiles is replaced with torched fly ash, which makes this method especially appropriate for sustainable buildings. Key performance indicators that show how effective these tiles are in maximizing energy use in buildings include thermal emissivity (0.874), solar reflectance (0.8), and solar absorption (0.256). While supporting more ecofriendly building techniques, this study highlights the advantages of utilizing burned fly ash in solar PV systems: enhanced power generation and thermal comfort. The main results open a greater potential for fly ash use in different building materials. The use of torched fly ash in building materials enhances thermal insulation and structural integrity while lowering cooling costs, making it an ideal choice for eco-friendly construction and highlighting the potential for further research into environmentally responsible, energy-efficient solutions.

Short-term photovoltaic forecasting model with parallel multi-channel optimization based on improved dung beetle algorithm

Accurate prediction of photovoltaic(PV) generation plays a vital role in power dispatching and is one of the effective ways to ensure the safe operation of power grid. In response to this issue, this paper improves the Rhino beetle optimization algorithm (LSDBO) using Logistic chaos mapping and sine function strategies an optimizes the PCL-MHA model (running CNN-MHA and LSTM-MHA models in parallel, PCL; Multi-Head-Attention, MHA) to enhance predictive accuracy. Various experiments were conducted using historical data from the Alice Springs PV system in Australia. PV component technologies comprise monocrystalline silicon and polycrystalline silicon, with array fixed on the ground. Through experiments, the proposed model in this paper achieved the best results in 16 metrics under different weather conditions, with average values of 98.43 % for R2, 2.69 % for MSE, 7.8 % for MAE, and 15.09 % for RMSE. Compared to other models, an average improvement of 2.41 %, 6.6 %, 7.77 %, and 11.21 % in these metrics.

Preparation of Si/TiSi2 as high-performance anode material for lithium-ion batteries by molten salt electrolysis

The photovoltaic industry has generated a large amount of silicon cutting waste (SiCW), whose disposal presents an urgent environmental issue. In this study, micron-sized flaky silicon cutting waste was transformed into silicon nanowires, and Si/TiSi2 nanocomposites were synthesized through molten salt electrolysis using photovoltaic SiCW and TiO2 as precursors. Lithium-ion batteries using the resulting composites as an anode exhibited an initial discharge specific capacity of 1936.1 mAh g⁻¹ and an initial Coulombic efficiency (ICE) of 83.99 %. After 200 cycles, its reversible specific capacity reached 1133.8 mAh g⁻¹, surpassing that of the molten salt electrolytic pre-oxidized SiCW (535.5 mAh g⁻¹) and untreated SiCW (385.0 mAh g⁻¹). This study presents a novel approach for modifying silicon-based anode materials while offering a sustainable and environmentally friendly method for recycling photovoltaic silicon waste.

Supporting strategy for investment evaluation of photovoltaic power generation engineering projects using multi-criteria decision analysis methods

This scientific study examines the evaluation of photovoltaic power generation projects through the application of multi-criteria decision analysis methods. Two groups of large-scale grid-connected PV power generation system projects with a nominal power of 50 MW and 500 MW respectively were analyzed and evaluated. These systems were designed to be installed in the same wider geographical area in northern Greece, but they were differentiated in the part of the PV circuit. Twelve systems were analyzed in which either monocrystalline silicon panels or poly-crystalline silicon panels or bifacial photovoltaic panels were to be installed. In these systems either central photovoltaic inverters or photovoltaic string inverters were considered for installation. The following criteria were used to evaluate the investment in these projects. These criteria were related to the profitability, the financial cost, the technical level, and the electrical energy production of the systems and these were the initial investment cost, the operation and maintenance cost, the levelized cost of electricity, the net present value, the internal rate of return, the capital recovery or payback period, the technical level of the photovoltaic circuit, the technical maturity of the photovoltaic circuit, and the annual electricity production. The evaluation of these criteria was initially conducted with fixed weighting coefficients followed by a sensitivity analysis of these weighting coefficients. The results of the evaluation using the PROMETHEE, AHP and TOPSIS multi-criteria decision analysis methods showed that the PV power generation systems which should be preferred are those with increased nominal power, where monocrystalline silicon technology panels are employed following the central inverter topology.

Highly reliable anti-reflection radiative cooling glass applicable to thermal management of solar cells

The encapsulation materials of solar cells have a significant impact on the performance and stability of the cells. Herein, an anti-reflection radiative cooling (ARRC) glass for photovoltaic (PV) devices is proposed by multi-layer design. Harnessing the synergy of anti-reflection layers and a transparent radiative cooling layer, ARRC glass can dissipate heat radiatively through molecular vibrations. Concurrently, it maintains the functionality and aesthetics of the associated devices. ARRC possesses four prominent characteristics, enabling it to serve as an encapsulation glass to enhance the performance and stability of solar cells. 1. Superior maximum visible light transmittance (0.954, 602 nm). 2. Outstanding mid-infrared emittance (0.951). 3. Excellent UV blocking performance (reached 99 % at 320 nm). 4. Marvelous thermal management performance (6.6 °C cooling for multi-crystalline silicon solar cells and 8.6 °C cooling for perovskite cells). Excellent anti-reflection and cooling performance of ARRC glass improves conversion efficiency by 1.08 % and 1.79 % for multi-crystalline silicon solar cells and perovskite solar cells (PSCs), respectively. Moreover, ARRC glass enhances the UV stability of PSCs by 4 times and significantly alleviates the thermal decomposition of PSCs. The ARRC glass, with excellent adhesion, scalability, economy, and stability, is expected to be applied on a large scale and further contribute to energy and environment sustainability.

A novel dual functional gradient Zn(O,S)/Mg electron-selective contact for dopant‐free silicon solar cells with efficiencies approaching 21 %

Dopant-free carrier-selective contacts have the potential to mitigate or eliminate parasitic absorption, auger recombination losses, etc. Therefore, the vigorous development of dopant-free carrier-selective contact materials is an important way to enhance the performance of crystalline silicon (c-Si) photovoltaics. This study presents the concept of magnetron sputtering gradient deposited zinc oxide (Gd-Zn(O,S)) combined with a low work function magnesium metal layer. Subsequently, the Gd-Zn(O,S)/Mg bifunctional layer was further investigated and optimised to determine its suitability as a contact layer for electron transfer in c-Si solar cells. This strategy simultaneously enables a good passivation and a low contact resistance. The c-Si(n)/a-Si:H(i)/Gd-Zn(O,S)/Mg devices are constructed and achieved an optimal contact recombination current density (J0) of approximately 1.51 fA cm−2, along with a minimum ρc of approximately 35.89 mΩ.cm2. As a consequence, the power conversion efficiency of a prototype silicon heterojunction solar cell is 20.92 %. This study demonstrates that the strategy of replacing the a-Si:H(n) electron transport layer with Gd-Zn(O,S) is an effective approach for improving the SHJ cell. This study also provides new perspectives for designing novel dopant-free carrier-selective contact structures.

Yield Performance of Standard Multicrystalline, Monocrystalline, and Cast-Mono Modules in Outdoor Conditions

On the journey to reduce the cost of solar modules, several silicon-growing techniques have been explored to grow the wafers the cells are based on. The most utilized ones have been the multicrystalline silicon (mc-Si) and the monocrystalline ones, with monocrystalline grown by the Czochralski (Cz) technique being the current winner. Cast-mono (CM-Si) was also largely employed during the last decade, and there are several gigawatts (GWs) of modules on the field, but no data were shared on the performance of those modules. In this study, we put three small installations next to each other in the field consisting of 12 modules each, with the only difference being in the wafers technology employed: mc-Si, CM-Si, and CZ-Si. The first two systems have been manufactured with the same equipment and had their field performance closely monitored for three years, while the CZ-Si one has been monitored for 17 months. The performance data shared show that CM-Si performance on the field is better than mc-Si and is very similar to CZ-Si, with no abnormal degradation. CM-Si requires less energy than CZ-Si to be manufactured, and high efficiencies have been reported; the field performance suggests that it is a very valid technology that deserves further exploration.

Multilayer Reconfigurable 3D Photonics Integrated Circuits Based on Deposition Method

AbstractPhotonics integrated circuits (PICs) can overcome the bottlenecks in communication capacity. 3D PIC technology is an attractive method for increasing density effectively and combining different materials on one chip for functional integration. In this study, a low‐cost and reconfigurable 3D integrated silicon photonics (SiPhs) platform is proposed fabricated by depositing polycrystalline silicon (poly‐Si) on crystalline silicon (c‐Si), which is patterned through deep ultraviolet (DUV) stepper‐based manufacturing process. The high mobility of poly‐Si ensures high‐speed and power‐efficient modulation. Based on the proposed 3D SiPhs platform, an 8 × 8 optical switch whose units are separated in different layers is fabricated and packaged. The switch shows average insertion losses of −13.98 and −15.86 dB, while working in “all‐cross” and “all‐bar” states, respectively. The crosstalk is lower than −19 and −11 dB for “all‐cross” and “all‐bar” states. Additionally, an overlayer switch located on the 1st and 3rd layers is proposed and experimentally demonstrated, which offers overlapping capabilities that are more compact compared with switches in a single‐layer platform. This validates the possibility of the large‐density integration scalability of the platform.

Enhancing interfacial stability in lithium orthosilicate/polymer blended novel hybrid solid-state electrolytes for all-solid-state lithium metal batteries

Hybrid solid-state electrolyte (HSSE) is a key component for the advancement of all-solid-state lithium metal batteries. The key challenges with the existing HSSEs are to ensure high ionic conductivity, activate dead inorganic/organic interface, and stimulate interfacial stability with electrodes. In this study, a novel HSSE is fabricated by integration of appropriately engineered end-of-life photovoltaic recycled high purity silicon derived nano size inorganic lithium orthosilicate and poly (vinylidene fluoride-co-hexafluoropropylene) polymer matrix through entrapping ionic liquid electrolytes. The obtained lithium orthosilicate-polymer blended HSSE is self-standing, soft, and flexible which delivers a low activation energy, leading a high ionic conductivity of 4.4 × 10−4 Scm−1. A critical lithium plating/stripping behaviour shows improved interfacial stability (both inorganic/organic interface and interfaces of HSSE/electrodes) under different current densities (0.05 mA cm−2 to 0.13 mA cm−2) when a drop of ionic liquid electrolyte is added, permitting cycling of an all-solid-state full cell (Li/HSSE/LiFePO4) at room temperature with high capacity (132 mAh g−1), stable cycle life and high Coulombic efficiency (initial ∼98 %; subsequent >99.5 %). Shaping the interfaces between inorganic/organic phases in the HSSE as well as the interfaces between electrodes/HSSE appears to be a workable path towards constructing very effective HSSE for the advancement of all-solid-state lithium metal batteries.

Solar Cells on Multicrystalline Silicon Thin Films Converted from Low‐Cost Soda‐Lime Glass

AbstractFabrication and characterization of solar cells based on multicrystalline silicon (mc‐Si) thin films are described and synthesized from low‐cost soda‐lime glass (SLG). The aluminothermic redox reaction of the silicon oxide in SLG during low‐temperature annealing at 600 – 650 °C leads to an mc‐Si thin film with large grains of lateral dimensions in the millimeter range, and moderate p‐type conductivity with an average Al acceptor concentration between 5 × 1016 and 1.2 × 1017 cm−3 in the bulk. A residual composite layer of mainly alumina and unreacted Al forms beneath the mc‐Si thin film as the second product of the crystalline silicon synthesis (CSS) process, which can be used as rear contact in a vertical solar cell design. The mc‐Si absorber (≈10 µm) is thin enough that the diffusion length given by a minority carrier lifetime of ≈1 µs exceeds the path length to the top contact several times. Homojunction and heterojunction diodes have been fabricated on the mc‐Si thin films and show great potential of CSS for the realization of high‐performance solar cells.

Voltage root mean square error calculation for solar cell parameter estimation: A novel g-function approach

The existing research on estimating solar cell parameters mainly focuses on minimizing the Root-Mean-Square Error (RMSE) between the estimated and measured current values of solar cells (referred to as the RMSEI). This involves using an analytical expression for current - I as a function of voltage - U (I = f1(U)) expressed through the Lambert W function. This paper introduces a new analytical solution for calculating the RMSE between measured and estimated solar cell voltages (referred to as the RMSEU). The formula is derived using the g-function or LogWright function, which provides a numerically applicable method for representing the analytical relation between solar cell voltage and current (U = f2(I)). Moreover, the paper presents the original formulas for calculating Mean Absolute Error (MAE) and Mean Absolute Percentage Error (MAPE) for solar cell voltages expressed through the g-function. The paper also compares various published approaches and examines two well-known solar cells/modules, namely the RTC France solar cell and the SOLAREX MSX–60 PV solar module, in terms of the RMSEU and single-diode solar cell models. Additionally, a novel metaheuristic algorithm, known as the Chaotic Walrus Optimization Algorithm (Chaotic-WaOA), is proposed for solar cell parameter estimation. This algorithm is applied to both mentioned solar cells to determine their parameters in terms of minimal RMSEU. In order to verify the proposed research, experimental observations were conducted on a 60Wp monocrystalline solar module installed at the Faculty of Sciences and Mathematics in Niš, Serbia. This was done using a specialized PV-KLA apparatus under different outdoor conditions. The research was also verified with a Cadmium telluride solar module (CdTe75638) and a multi-crystalline silicon solar module (mSi0188). The investigation results demonstrate the accuracy, applicability, and numerical feasibility of the proposed RMSE expression and algorithm. Additionally, the study confirms the applicability of the g-function in invertible solar cell modeling.

Lithium-based water-absorbent hydrogel with a high solar cell cooling flux

The lifetime and photovoltaic conversion efficiency of the solar cell will decline as the temperature rises. Herein, a versatile hydrogel allowing atmospheric water harvesting and evaporative cooling is introduced to passively reduce the working temperature of the solar cell. As a flexible substrate, the lithium-rich and highly absorbent polyacrylamide hydrogel is employed to satisfy these specifications. Preferentially, the water-saturated hydrogel, which is bonded to the backside of the solar cell, collects the waste heat produced by the cell and dissipates it into the atmosphere by water evaporation. Importantly, the hydrogel naturally gathers atmospheric vapor at night or on overcast days to revive its cooling ability. This configuration endows the PV cell with a cooling flux of up to 529 W m−2 and thus reduces the working temperature of a polycrystalline silicon cell by 26 °C at 1 sun (=1 kW m−2) illumination. More importantly, the hydrogel arrangement supports 6.2 % and 17 % improvements in average open-circuit and maximum power output (or photovoltaic efficiency), respectively. This is devoid of limits on access to liquid water resources, making it a potential option for efficient and sustainable solar cell power generation.

Wettability and infiltration of molten Si on SiO2 substrate containing porous Si3N4 coating: Influence of α-Si3N4 coating and β-Si3N4 coating

Photovoltaic (PV) multicrystalline silicon (Si) is currently grown in SiO2 crucible with porous α-Si3N4 coating, which serves as interfacial releasing agent to avoid sticking. Compared with α-Si3N4, β-Si3N4 should be another potential coating material, due to the same chemical composition and better structural stability. To verify this conception, it's of great importance to ascertain the wetting behavior and infiltration of Si/β-Si3N4/SiO2 ternary system. In this study, the sessile drop technology and micro-structural analysis method were used to investigate interfacial wetting behavior and infiltration of Si drop on different coatings, which are α-Si3N4 coating, β-Si3N4 coating and silica modified β-Si3N4 (β-Si3N4@SiO2) coating. The results show that wettability transformation (from non-wetting to wetting) commonly occurs for all coatings, as well as infiltration. The β-Si3N4 coating displays much shorter non-wetting duration and severer infiltration than α-Si3N4 coating. Compared with β-Si3N4 coating, the β-Si3N4@SiO2 coating exhibits significantly extended non-wetting duration and considerably delayed infiltration. These differences about wettability and infiltration are strongly associated with O content in all coatings and de-oxidation. This work clarify the wettability/infiltration differences between α-Si3N4 coating and β-Si3N4 coating in Si/Si3N4/SiO2 ternary system, and could be used to develop novel β-Si3N4 coating with low cost for PV multicrystalline Si manufacture.

Material Removal Mechanisms of Polycrystalline Silicon Carbide Ceramic Cut by a Diamond Wire Saw.

Polycrystalline silicon carbide (SiC) is a highly valuable material with crucial applications across various industries. Despite its benefits, processing this brittle material efficiently and with high quality presents significant challenges. A thorough understanding of the mechanisms involved in processing and removing SiC is essential for optimizing its production. In this study, we investigated the sawing characteristics and material removal mechanisms of polycrystalline silicon carbide (SiC) ceramic using a diamond wire saw. Experiments were conducted with high wire speeds of 30 m/s and a maximum feed rate of 2.0 mm/min. The coarseness value (Ra) increased slightly with the feed rate. Changes in the diamond wire during the grinding process and their effects on the grinding surface were analyzed using scanning electron microscopy (SEM), laser confocal microscopy, and focused ion beam (FIB)-transmission electron microscopy (TEM). The findings provide insights into the grinding mechanisms. The presence of ductile grinding zones and brittle fracture areas on the ground surface reveals that external forces induce dislocation and amorphization within the grain structure, which are key factors in material removal during grinding.

Hydrogenation by catalytically generated atomic hydrogen for passivating contacts in crystalline silicon solar cells

Hydrogenation employing catalytically generated atomic hydrogen (Cat-H) is implemented on stacks of n-type polycrystalline silicon (poly-Si)/Si oxide (SiOx) to enhance passivation quality. The utilization of Cat-H demonstrates a substantial enhancement in surface passivation quality on crystalline Si (c-Si), resulting in an increase of the effective minority carrier lifetime (τeff) from 2.0 to 3.9 ms. The investigation reveals a dependency of τeff on the duration of Cat-H treatment: an initial rise followed by a plateau or slight decline. Secondary ion mass spectrometry (SIMS) measurements revealed the diffusion of H atoms into poly-Si and c-Si, which accumulate at the poly-Si/c-Si interface. This accumulation terminates dangling bonds in the poly-Si layer on the c-Si surface. Furthermore, the presence of an ultra-thin thermal Si oxide layer on the poly-Si layer formed during high-temperature annealing is crucial for protecting the film against etching induced by Cat-H.

Simple synthesis of weather-resistant and self-cleaning anti-reflective coating for enhancing photovoltaic conversion efficiency

Transparent self-cleaning coatings have garnered significant attention for their promising prospects in outdoor applications, particularly in solar panels and high-end optical devices. However, existing technologies still grapple with the challenges of achieving high transmittance and superior weather resistance. Therefore, developing cost-effective coatings that possess both high transparency and excellent durability is paramount. A novel method for synthesizing an anti-reflective (AR) coating is presented in this paper, offering simplicity, cost-efficiency, and high performance. By merging acid-base catalyzed sol-gel chemistry with the dip-coating process, the coating's transparency, durability, and hydrophobicity are notably improved. Production time is significantly reduced through process optimization. The AR coating achieves an exceptional transmittance of 97.3 % at 620 nm, a 6.7 % increase over that of untreated glass. Furthermore, its 145° water contact angle demonstrates excellent hydrophobicity and self-cleaning properties. Mechanical stability tests indicate that the coating retains over 96 % transmittance even after 30 tape adhesion cycles. Long-term UV exposure tests reveal that the coating's transmittance and contact angle remain almost unchanged, underscoring its superior environmental stability and weather resistance. Additionally, the coating enhances the transmittance of multi-crystalline silicon (mc-Si) solar cells compared to commercial glass, boosting the photovoltaic conversion efficiency from 11.04 % to 11.81 %, an increase of 7 %. With these exceptional properties, this coating holds significant potential for applications in mc-Si solar cells and high-end optical devices, providing the industry with an efficient and economical solution.

22.56% total area efficiency of n-TOPCon solar cell with screen-printed Al paste

Screen-printing Ag paste on the rear side of the Tunnel Oxide Passivated Contact solar cells (TOPCon) is still the mainstream method to form electrodes. However, the high price of precious metals increases the cost of TOPCon cells. Al is a cheap and high-performance conductor, and its work function is compatible with the rear side of TOPCon cells. In this study, we used a UV pulse laser (355 nm, 10 ps) to ablate the rear side SiNx passivation layer of TOPCon cells and then printed Al paste with different weight percentages of silicon (Si-wt.%) on the phosphorus-doped polycrystalline silicon (n+-poly-Si) layer to reduce the cost. We investigated the damage mechanism of laser on SiOx/n+-poly-Si/SiNx passivation structure and the contact mechanism between Al paste and n+-poly-Si layer. The results show that the Voc of SiOx/n+-poly-Si/SiNx passivation structure reduced about 6–7 mV when the laser energy density was 0.431 J/cm2. We got the best electrical performance of TOPCon cells printed with Al paste (25 wt%-29 wt% silicon). The open-circuit voltage (Voc) and the conversion efficiency (Eff), have reached 663.60 mV and 22.56 % respectively. Although the efficiency was 9.40 % relative lower than that of TOPCon cells printed with Ag paste, but the cost of Al paste only accounted for 10 % of Ag paste. In the future, the highest Eff of TOPCon solar cells printed with Al paste on the rear side are expected to reach the commercial TOPCon based on Ag paste, which applies laser doping selective emitter technology (SE) and bifacial poly-Si passivation structure.

Cuboids Prevail When Unraveling the Influence of Microchip Geometry on Macrophage Interactions and Metabolic Responses.

Drug delivery advances rely on using nano- and microsized carriers to transfer therapeutic molecules, although challenges persist in increasing the availability of new and even approved pharmaceutical products. Particle shape, a critical determinant in how these carriers distribute within the body after administration, raises opportunities of using, for instance, micrometer-sized nonspherical particles for vascular targeting and thereby creating new prospects for precise drug delivery to specific targeted areas. The versatility of polycrystalline silicon microfabrication allows for significant variation in the size and shape of microchips, and so, in the current work, photolithography was employed to create differently shaped polysilicon microchips, including cuboids, cubes, bars, and cylinders, to explore the influence of particle shape on cellular interactions. These microchips with different shapes and lateral dimensions, accounting for surface areas in the range of ca. 15 to 120 μm2 and corresponding total volumes of 0.4 to 27 μm3, serve as ideal models for investigating their interactions with macrophages with diameters of ca. 20 μm. Side-scattering imaging flow cytometry was employed for studying the interaction of label-free prepared microchips with RAW 264.7 macrophages. Using a dose of 3 microchips per cell, results show that cuboids exhibit the highest cellular association (ca. 25%) and uptake (ca. 20%), suggesting their potential as efficient carriers for targeted drug delivery to macrophages. Conversely, similarly sized cylinders and bar-shaped microchips exhibit lower uptakes of about 8% and about 6%, respectively, indicating potential benefits in evading macrophage recognition. On average, 1-1.5 microchips were internalized, and ca. 1 microchip was surface-bound per cell, with cuboids showing the higher values overall. Macrophages respond to microchips by increasing their metabolic activity and releasing low levels of intracellular enzymes, indicating reduced toxicity. Interestingly, increasing the particle dose enhances macrophage metabolic activity without significantly affecting enzyme release.