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Highly sensitive, simple and reliable colorimetric probe for Cu

In this work, a high-density hydrogen (HDH) treatment is proposed to reduce interface traps and enhance the efficiency of the passivated emitter rear contact (PERC) device. The hydrogen gas is compressed at pressure (~ 70 atm) and relatively low temperature (~ 200 °C) to reduce interface traps without changing any other part of the device’s original fabrication process. Fourier-transform infrared spectroscopy (FTIR) confirmed the enhancement of Si–H bonding and secondary-ion mass spectrometry (SIMS) confirmed the SiN/Si interface traps after the HDH treatment. In addition, electrical measurements of conductance-voltage are measured and extracted to verify the interface trap density (Dit). Moreover, short circuit current density (Jsc), series resistance (Rs), and fill factor (F.F.) are analyzed with a simulated light source of 1 kW M−2 global AM1.5 spectrum to confirm the increase in cell efficiency. External quantum efficiency (EQE) is also measured to confirm the enhancement in conversion efficiency between different wavelengths. Finally, a model is proposed to explain the experimental result before and after the treatment.

In the present study, Ag and Cu metal-assisted chemical etching (MACE) technique was used for etching single-crystalline silicon at 15–25 °C, followed by post-processing with the HF/HNO3/H2O solution. Further, the relationship between the shape of the cross-section of the pore and the quality of passivation was deciphered. The parameters Jo1, minority carrier lifetime, and surface recombination velocity were measured, and the correlation between these three parameters and the open-circuit voltage (Voc) value was determined for all solar cells. The changes in the reflectance, solar flux density, and external quantum efficiency with changing wavelength were analyzed, and the relationship of these changes with short-circuit current density was determined. The Voc of all Ag-MACE solar cells is greater than that of all Cu-MACE solar cells, although the efficiency of almost all Cu-MACE solar cells is higher than that of the Ag-MACE solar cells. Furthermore, the electroluminescence image, the adhesion between the silver electrode and the pore, the quality of the aluminum back surface field, the metal residues on the surface, and the bulk of the wafer were systematically investigated. The best solar cell efficiency obtained for Ag-MACE and Cu-MACE PERC structures was 18.68% and 19.32%, respectively.

Improving material and interface defects are an important issue in reducing solar cell leakage current and enhancing their efficiency. From back surface field (BSF)-based solar cell to passivated emitter and rear cell (PERC), solar cell structures have been designed to reduce defects. In this study, a supercritical fluid (SCF) technique is applied as a low temperature defect passivation technology to passivate defects in a PERC solar cell, enhancing device performance. Owing to the high penetration and high solubility of the supercritical fluid, hydrogen is the passivation source carried into the device to passivate Al2O3/Si interface defects. Furthermore, electronic analysis is used to confirm the benefits of the SCF treatment on the solar cell properties of open-circuit voltage (Voc), short-circuit current (Jsc), fill factor (FF), efficiency, power (Pmax) and series resistance (Rs), all measured under a standard light source. Finally, a model is proposed to explain how the SCF treatment passivates interface defects and enhances device performance.

This paper explores the utility of single-crystalline silicon solar cells that are treated with the screen-print technique to implement line contacts at the cells’ rear surfaces. We designed rear-surface line-contact (RSLC) solar cells using screen-print methods on n-type wafers (125 ×125 mm2) in order to produce rear surface passivation layers. The performances of these cells were then evaluated and compared to laser fired contact solar cells. We examined the rear surface passivation quality of a stack consisting of an aluminum oxide (Al2O3) passivation layer deposited by atomic layer deposition, overlaid with a silicon nitride (Si3N4) layer deposited by plasma-enhanced chemical vapor deposition. The initial outstanding surface passivation quality provided by the Al2O3/Si3N4 stacks remained high after annealing, as indicated by the average light-beam-induced-current value (85.1 mA/cm2) for the developed RSLC cells. RSLC cells exhibited conversion efficiencies of up to the optimal 18.48%, demonstrating that line-contacting processes were consistent with print screen and that the simplification of electrode process may be realized for industrial applications.

In this paper, we demonstrate new electrode pattern on rear side of p-type bifacial passivated emitter and rear cells (bifacial-PERC) solar cells for reducing series resistance loss caused by the aluminum grid lines. Cell efficiency of bifacial PERC is enhanced by rear Al grids add multi bus-bar (MBB) or grid segments interconnection. The high J sc and FF value of the PERC+ using local grid with MBB as rear electrodes which increases the J sc by 0.5 mA/cm2 and FF by 2.58 % compare to the PERC+ without rear MBB. The high Jsc and FF value of the PERC+ using local grid with vertical line segments as rear electrodes which increases the J sc by 0.34 mA/cm2 and FF by 3.6 % compare to the PERC+ without vertical line segments. In contrast to the PERC cell, the bifacial PERC cell using localized Al grid on rear side and with thicker back surface field (BSF).

Previous studies have considered the same temperature for all components of the silicon etching solution, and the effect of the temperature of the individual components on the etching results has not been explored. In the present study, a diamond-wire-sawn (DWS) multi-crystalline silicon wafer was etched twice for 50 s each time. The initial temperature of HF was selected to be room temperature, 55 and 66 °C, whereas those of H2O2 and Cu(NO3)2 varied between 40 and 70 °C, 40 and 72 °C, respectively. The temperature of the three components of the solution was allowed to change over time. The effects of H2O2, Cu(NO3)2, and HF temperatures on the etch morphology, reflectivity, and energy conversion efficiency of the fabricated solar cells were investigated. The saw marks of a DWS wafer were determined to be the preferred nucleation sites for the formation of the inverted pyramid (IP) structure. The optimum temperatures for etching Si to obtain a large area of IP structure were ~72 °C for Cu2+, ~25 °C for HF, and ~55 °C for H2O2. The strong isotropic etching ability of high-temperature HF caused the silicon crystal surface to deviate from the IP structure and left many recombination centers on the surface. A wafer with an IP structure on the entire surface exhibited the highest energy conversion efficiency of 18.21%. A simple wet-chemical post-processing step is expected to reduce the recombination centers and improve the energy conversion efficiency of the fabricated solar cell.

In this paper, we proposed a significant improvement for cell efficiency of 1.2%$_{\mathbf {abs}}$ by optimizing the front side structure of PERC solar cells without any additional equipment. The feasible achievement includes triple silicon oxynitride anti-reflection coating (ARC) layers which absorb more incident light for base than silicon nitride single layer. Knotless screen printing with fine-line finger of 23 $\mu \textbf{m}$ width compares to that of conventional screen printing. Moreover, multi-busbars contact pattern was optimized instead of four busbars contact pattern. As a result, the best efficiency of PERC solar cells of 21.51% with an area size of 244.32 cm$^{\mathbf {2}}$textbf was obtained, which can be utilized for industrial production.

This study proposes a promising silicon (Si) solar cell structure for reducing the potential induced degradation (PID) of crystalline Si solar cells. Phosphorous silicate glass (PSG) layers were carefully designed on an emitter layer, and the thickness of these layers (dPSG) was controlled by adjusting the diffusion temperature and time. The results show that the power loss remarkably decreased from 31% (dPSG = 0 nm) to 11% (dPSG = 22.3 nm) and further decreased to less than 5% after a 48-h PID test when dPSG was higher than 23.3 nm. No additional process or equipment was required for producing this effective and low-cost solar cell. © The Author(s) 2015. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any

In this paper, we identify the influences of different annealing conditions on the p-type Cz silicon wafer surfaces and solar cells. X-ray photoelectron spectroscopy (XPS) has been applied to surfaces of silicon wafers for evaluating the composition. In order to identify the properties of the defect, minority carrier lifetime measurement was performed. Annealing condition effected the silicon surface oxidation and the defect of silicon. The best cell efficiency of 20.07 % with an open circuit voltage (Voc) of 648 mV was achieved by annealed at an oxygen atmosphere.

This article investigates the effects of sheet resistance on a selective emitter (SE) solar cell fabricated using a simple laser doping process (LD). In order to demonstrate the influence of lightly doped emitter we divided cells for three groups for POCl3 diffusion with sheet resistance of 100 Ω/sq (SE-1), 120 Ω/sq (SE-2) and 140 Ω/sq (SE-3). After laser doping, the sheet resistance is ∼60 Ω/sq for silver electrode contact. The optimal cell with sheet resistance values of 60/120Ω/sq showed the best efficiency (η) of 20.11 %, open circuit of 650 mV.

To ensure reliable test data communication in a wireless test system, information can be encapsulated in packets equipped with error correction and retransmission capability. Systems employing such an approach require a complex test interface (test wrapper) to bridge communication and test modules. This article proposes a modular test wrapper design and an automation tool to create a wrapper for a target circuit under test and associated test program.

Thin silicon foils with two different crystal orientation were fabricated by SLiM-cut method. The thickness of the and foils are 45 µm and 33 µm, respectively. The surface quality was compared in this study. The foil have smoother surface than the foil. 4cm2 thin silicon solar cells with heterojunction structure were fabricated. The efficiency was found to be 10.74% and 12.81% for the and solar cell, respectively. The surface quality of the silicon foils was found to affect the solar cell character. However, the Voc of solar cell is higher than solar cell. It was believed that the local epitaxial occur when the amorphous silicon was deposited on the surface. The increasing of dangling bonds will become the recombination center and reduced the Voc of solar cell.

Previous literature has shown that poly(vinylidene fluoride)-graft-poly(styrene sulfonated acid) (PVDF-g-PSSA) exhibits a lower methanol permeability than commercial Nafion and so is better suited to use as a proton exchange membrane (PEM) in direct methanol fuel cells (DMFCs). A number of studies have suggested that the microstructures of ionic aggregates explain their lower methanol permeability, but few direct morphological observations have been reported. In this study, the use of a tapping mode atomic force microscope (AFM) and a high-angle annular dark-field (HAADF) scanning transmission electron microscope (STEM) has identified the phase separation of PVDF and sulfonated PS, and ionic sulfonic aggregates, 3–5 nm, in sulfonated PS regions. An experiment to elucidate the microstructural changes in the membrane with and without methanol immersion shows that PVDF-g-PSSA has ionic aggregates with a more stable microstructure than Nafion.

Screen-printed aluminum local back surface field (Al-LBSF) solar cells are a promising candidate for high-efficiency industrial silicon-based solar cells. For improving the conversion efficiency, industrial LBSF cell process flows typically comprise rear side planarization to reduce the surface roughness. In this paper, we investigate the influences of rear surface topographies on wet chemical polishing LBSF cells. The best conversion efficiency of 19.09% on screen-printed LBSF cell with polished rear surface was demonstrated.

This study focuses on two novel approaches (co-firing and non-cofiring) for metal wrap through (MWT) solar cell fabrication and compares their electric properties using DuPont MWT specialized paste. The co-firing process involves 3 printing steps followed by co-firing of metallization contacts. The non-cofiring process involves sequential processing steps: first printing and firing of rear aluminum and front Ag finger; thereafter via and rear busbar printing and IR drying at 400°C. The best cell efficiency of 17.0% was demonstrated in this work based on 200 μm thick multi-crystalline silicon having an area of 125×125 mm2. On average, MWT cells showed 0.3~0.4% efficiency gain compared to conventional cells, due to 2% higher short circuit current (Isc). Although the shunting resistance of conventional solar cells is still slightly better than the two MWT approaches, results indicate that both MWT cells maintained good shunt performance and did not negatively impact fill factor (F.F.). The depth of vias is only 200 μm so that the contribution of via paste on Rs was concluded to be negligible compared to other dominating resistances. The electrical characteristics demonstrated in this work indicate that both MWT approaches proposed are reliable and industrially feasible.

We applied the deactivation treatments to p-type single crystalline silicon solar cells for deactivating the recombination-active boron-oxygen complex. The methods we used include thermal annealing treatment, capacitively couple plasma (CCP) treatment, and plasma immersion ion implantation (PIII) treatment. The results showed that all the deactivation treatments were working and the energy transfer efficiency (Eff) was thereby increased by more than 1% absolute compared to the degraded state base on the increasing of the open-circular voltage (Voc) and short-current density (Jsc). The CCP deactivated treatment got better efficiencies than PIII treatment because the PIII treatment damaged the surface of solar cells. After the forming gas treatment, the samples could be improved to close to the PIII samples due to the surface damage repairing. However, the increased efficiency could not be kept and would be degraded again after illumination.

In this paper, we show that cell efficiency can be improved by simple preclean steps for silicon substrates. A very low reflectance of less than 1% is observed in the wavelength range from 450 to 700 nm for the silicon substrates precleaned using a NaOH solution followed by a gettering process. Lifetime measurements show that the silicon substrates treated by these preclean processes have a significantly improved minority carrier lifetime owing to a better surface condition than untreated silicon substrates. This result is further supported by the performance of the solar cells. A cell efficiency of 18.609% is achieved in the treated silicon substrates with a gain of 2.14% compared with the untreated silicon substrates.