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Design, Fabrication, and Characterization of n-Si IBC Solar Cells Using PERC Technology
摘要： In this article, high-efficiency n-Si interdigitated back contact solar cells (IBC) were fabricated with the perc-like process. The cell was demonstrated with the efficiency of 22.16% (cell area = 10 × 10 cm), open-circuit voltage of 685 mV, short-circuit current density of 41.21 mA/cm2, and fill factor of 78.48%. The low fill factor can be attributed to the high base recombination taking place under high-level injection. Fill factor over 81% and, therefore, cell efficiency over 23% is expected when wafers of high bulk lifetime (τ bulk ≥ 10 ms) or low resistivity (ρ ≤ 1 Ω·cm) are used. The light I–V curve was fully characterized with the optical and electronic properties obtained from independent measurements.
关键词： passivated emitter and rear cell (PERC),Interdigitated-back-contact cell (IBC)
更新于2025-09-16 10:30:52
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High‐precision alignment procedures for patterning processes in solar cell production
摘要： We present two approaches for high-accuracy aligning of patterning processes with each other when fabricating solar cells. We introduce the approaches on the example of two different patterning processes of which one is adjustable (laser process) and one is not adjustable (screen-printing process). The basic idea is to measure the coordinates of the applied structures of each involved patterning process at discrete grid points with respect to a reference coordinate system. We chose the grid points such that they completely define the final cell pattern. Then, we adjust the grid point coordinates of one of the patterning processes (the laser process) according to the pattern of the other process (the screen-printing process). The laser then performs the patterning by connecting the corrected grid points with each other in the desired direction. We perform the associated high-precision measurement of the patterns' coordinates by using either a high-precision offline coordinate measuring machine or a high-resolution inline camera system with subsequent computer-based data processing. The latter inline method enables high throughput and is, in turn, of great interest for mass production of solar cells. In this paper, we demonstrate the alignment procedure approaches on “pPassDop” solar cells by adjusting a locally applied laser process to the directly following screen-printing step. This proof of principle includes both above-mentioned methods for coordinate determination in separate cell batches. Our innovative alignment procedures so far demonstrated the successful matching of 40-μm-wide screen-printed contact fingers to 70-μm-wide laser-processed lines over the entire area of 6-inch solar cells.
关键词： PERL,coordinate correction,silicon solar cells,patterning processes,selective emitter,PERC,bifacial,alignment,screen printing,pPassDop,laser
更新于2025-09-16 10:30:52
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Random nanohole arrays and its application to crystalline Si thin foils produced by proton induced exfoliation for solar cells
摘要： We report high efficiency cell processing technologies for the ultra-thin Si solar cells based on crystalline Si thin foils (below a 50 μm thickness) produced by the proton implant exfoliation (PIE) technique. Shallow textures of submicrometer scale is essential for effective light trapping in crystalline Si thin foil based solar cells. In this study, we report the fabrication process of random Si nanohole arrays of ellipsoids by a facile way using low melting point metal nanoparticles of indium which were vacuum-deposited and dewetted spontaneously at room temperature. Combination of dry and wet etch processes with indium nanoparticles as etch masks enables the fabrication of random Si nanohole arrays of an ellipsoidal shape. The optimized etching processes led to effective light trapping nanostructures comparable to conventional micro-pyramids. We also developed the laser fired contact (LFC) process especially suitable for crystalline Si thin foil based PERC solar cells. The laser processing parameters were optimized to obtain a shallow LFC contact in conjunction with a low contact resistance. Lastly, we applied the random Si nanohole arrays and the LFC process to the crystalline Si thin foils (a 48 μm thickness) produced by the PIE technique and achieved the best efficiency of 17.1% while the planar PERC solar cell without the Si nanohole arrays exhibit 15.6%. Also, we demonstrate the ultra-thin wafer is bendable to have a 16 mm critical bending radius.
关键词： proton implant exfoliation,random Si nanohole arrays,PERC solar cells,ultra-thin Si solar cells,light trapping,laser fired contact
更新于2025-09-16 10:30:52
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AIP Conference Proceedings [AIP Publishing INTERNATIONAL SYMPOSIUM ON GREEN AND SUSTAINABLE TECHNOLOGY (ISGST2019) - Perak, Malaysia (23–26 April 2019)] INTERNATIONAL SYMPOSIUM ON GREEN AND SUSTAINABLE TECHNOLOGY (ISGST2019) - Lead-free solders for ribbon interconnection of crystalline silicon PERC solar cells with infrared soldering
摘要： We report about the analysis of Pb-free, low-temperature solders for the ribbon-interconnection of PERC solar cells with an industrial infrared stringer. Five solders (SnPb, SnBi-A, SnBi-B, SnBiAg and a proprietary lead-free, low-temperature (PLFLT) alloy) are characterized with di?erential scanning calorimetry to determine the melting and solidi?cation temperature. It is found that SnBi-B, SnBiAg, and the PLFLT composition melt in a temperature range between 137 ?C to 171 ?C instead of a single temperature. Solidi?cation occurs at a 3 K to 11 K lower temperature (undercooling). Mono-crystalline silicon PERC cells are contacted using an industrial stringer. The microstructure of the solder bonds is investigated with scanning electron microscopy. For the SnBi-A-solder, large and brittle Bi-phases are identi?ed. The SnBi-B, SnBiAg and PLFLT solder show a ?ner grain structure. The added Ag in SnBiAg forms an intermetallic compound of Ag3Sn close to the Cu-core of the ribbon. The peel strength of the connected solar cells with the Pb-free solders is on average 1 N mm?1 or slightly higher. Some bonds show low adhesion. The observed fracture mode is mainly failure at the busbar metallization to solar cell irrespective of the solder type. However, the occasionally observed solder residues on the metallization clearly reveal brittle fracture for the Pb-free solders, which is not observed for SnPb. First reliability tests show similar degradation of 1 % to 2 % for all solders.
关键词： ribbon interconnection,infrared soldering,lead-free solders,crystalline silicon PERC solar cells
更新于2025-09-16 10:30:52
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Spray-Deposited Al <sub/>2</sub> O <sub/>3</sub> for Rear Passivation and Optical Trapping in Silicon Solar Cells
摘要： Low-cost spray deposition is employed to investigate the suitability of spray-deposited Al2O3 for rear passivation and optical trapping in passivated emitter rear contact (PERC) Si solar cells. Structural, optical, and electrical properties of spray-deposited Al2O3 ?lms are investigated. Capacitance-voltage measurements indicate that spray-deposited Al2O3 has a negative charge density of 3.19 × 1012 cm–2 for an 80-nm ?lm, suggesting that it can serve as the passivation layer. Optical properties of spray-deposited Al2O3 are identical to the Al2O3/SiNx stack prepared by atomic layer deposition and plasma-enhanced chemical vapor deposition, indicating that it can also serve as the optical trapping layer. Atomic force microscopy studies show that spray-deposited Al2O3 is crack and pore free, and its surface roughness has a root-mean-square value of 0.52 nm for an 80-nm ?lm. Spray-deposited Al2O3 is amorphous as determined by X-ray diffraction. X-ray photoelectron spectroscopy analysis suggests that spray-deposited Al2O3 is slightly Al-rich. The resistivity and breakdown ?eld of an 80-nm Al2O3 ?lm are 5.46 × 1014 Ω-cm and 3.28 MV/cm, respectively, which are stable after 800°C ?ring. These properties suggest that spray-deposited Al2O3 is a promising candidate to replace the Al2O3/SiNx stack in Si PERC cells.
关键词： Al2O3,spray deposition,rear passivation,Si PERC cells,optical trapping
更新于2025-09-12 10:27:22
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AIP Conference Proceedings [AIP Publishing 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Fes, Morocco (25–27 March 2019)] 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Adaptation of the industrial PERC solar cell process chain to plated Ni/Cu/Ag front contact metallization
摘要： Three approaches to close the efficiency gap between screen-printed Ag-paste and Ni/Cu/Ag-plated front contact metallization on industrial passivated emitter and rear cells (PERC) solar cells are presented in this paper. In the first approach, the POCl3 diffusion is adjusted to an emitter profile (reduced peak doping) for plated contacts. The second approach is to adapt the laser over doping (LOD) process of the phosphor silicate glass (PSG) to create the selective emitter to the properties of laser patterning and plating. In the third approach, we vary the process step order of front laser patterning and back side aluminum firing. The three approaches show very promising results. Efficiencies higher than 22% and open-circuit voltage VOC values of close to 680 mV are reached on a cell area of 251,99cm2. Overall the values excel the reference values obtained with screen printing and firing of Ag-paste. For future developments, VOC values between 685 mV and 690 mV and efficiencies around 22.5% seem very likely.
关键词： laser over doping,Ni/Cu/Ag-plated front contact,PERC solar cells,selective emitter,POCl3 diffusion
更新于2025-09-12 10:27:22
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AIP Conference Proceedings [AIP Publishing 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Fes, Morocco (25–27 March 2019)] 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Impact of the thermal budget of the emitter formation on the pFF of PERC+ solar cells
摘要： We develop processes for advanced phosphorus doping profiles in order to reduce the emitter saturation current density Jo,e of industrial bifacial PERC+ solar cells. With an in-situ oxidation, which takes place in the POCl3 furnace in between the deposition and the drive-in step, the surface concentration was lowered from 3 × 1020 cm-3 to 1.7 × 1020 cm-3. With an additional ex-situ oxidation, which takes place after the phosphorus silicate glass is removed, the phosphorus surface concentration was further reduced to 3 × 1019 cm- 3. The decreased phosphorus surface concentration drastically reduces Jo,e from 106 fA/cm2 down to 22 fA/cm2. The reduced Jo,e increases the implied open circuit voltage up to 712 mV of unmetallized PERC+ test structures and the Voc of PERC+ solar cells up to 678 mV and efficiencies up to 21.8%. However, our solar cell analysis reveals for the first time, that with increasing thermal budget of the applied POCl3 and oxidation recipes the pseudo fill factor (pFF) decreases by up to 1.5%. This corresponds to an efficiency loss of approximately 0.5%abs. We analyse the pFF loss based on different lifetime test structures representing the emitter or the bulk of the PERC+ solar cell. From the lifetime measurements we calculate I-V curves representing the implied fill factor (iFF) of the different parts of the PERC+ solar cell as well as a combined one for the whole cell, which compares well to the measured pFF. The iFF values clearly show that the pFF is mainly limited by wafer bulk material. However, also the iFF values of the emitter slightly decrease with increasing thermal budget.
关键词： in-situ oxidation,phosphorus doping profiles,pseudo fill factor,ex-situ oxidation,emitter saturation current density,PERC+ solar cells,thermal budget
更新于2025-09-12 10:27:22
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Potential-Induced Degradation of Bifacial PERC Solar Cells Under Illumination
摘要： Bifacial passivated emitter and rear cell (PERC) solar cells are promising candidates to reduce levelized cost of electricity since a rear-side power gain can be achieved with minor changes in cell production. However, in addition to the potential-induced degradation of the shunting type (PID-s), some bifacial solar cells may exhibit another degradation related to their rear side. Using three types of purchased industrial bifacial PERC cells encapsulated in our laboratory, we show that a rear-side PID test under simultaneous illumination can cause up to 14% power degradation, which is related to increased carrier recombination at the rear side of the cell. Thus, we ?nd that the degradation under realistic ?eld conditions is strong enough to signi?cantly reduce the bifaciality gains. This is of particular importance as only some of the investigated cells recover under dark conditions. Microstructural analysis of the PID-stressed rear side reveals localized permanent structural damages of the passivation layer leading to an increased rear-side recombination.
关键词： silicon corrosion,Bifacial solar cell,potential-induced degradation,passivated emitter and rear cell (PERC)
更新于2025-09-11 14:15:04
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AIP Conference Proceedings [AIP Publishing 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Fes, Morocco (25–27 March 2019)] 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Improvement of PERC solar cell efficiency based on laser-doped selective emitter
摘要： In recent years, high-efficiency solar cells have a strong competitiveness in the market and the p-type PERC solar cell is the mainstream product of leading cell manufacturers. To further improve the efficiency and reduce the cost, laser doping selective emitter (LDSE) has been introduced into the mass production line as a promising technology. In this work, we fabricated high efficiency PERC solar cells by using LDSE technique. Firstly, we adjusted the diffusion process and obtained the best sheet resistance (115 ± 5 ?/sq), which resulted in an efficiency gain of 0.11%. Subsequently, the best diffusion profile of the selective emitter was obtained through optimization. With the surface concentration of about 3.0×1020 atoms/cm3 and emitter depth of 0.32 μm, the optimum photovoltaic parameter gains have been achieved, namely 0.18% for Eff, 6.7 mV for Voc and 0.25 mA/cm2 for Jsc respectively. EQE measurements show that the spectral response can be improved in the short wavelengths through introducing LDSE structure. Correscan measurements indicate that the front contact resistance of SE solar cell was slightly higher than that of reference due to the lateral transport resistance. The efficiency of LDSE solar cell can be increased further by the optimization of laser uniformity and the alignment of screen-printed finger with heavily doped region.
关键词： LDSE,QE,PERC,ECV,diffusion
更新于2025-09-11 14:15:04
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AIP Conference Proceedings [AIP Publishing 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Fes, Morocco (25–27 March 2019)] 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Excess charge carrier injection densities in PERC solar cells at open-circuit voltage and maximum power point
摘要： Nowadays passivated emitter and rear contact (PERC) solar cells are mainstream cell technology. An accurate knowledge of the excess charge carrier injection density during illumination will help to understand the kinetic behavior of charge carrier sensitive defects such as boron-oxygen related defect, LeTID defect or FeB pair dissociation and thus supports reliability improvements of PERC cells. However, the excess charge carrier injection density is not easily accessible in experiments. The aim of our research is to investigate the distribution of the injection density in PERC cells in the range of 22% to 24% efficiency. Thus, we perform a numerically simulated Design of Experiment varying the base resistivity and the location of recombination to derive the excess charge carrier injection density. However, no relevant combined influences of the location of recombination on the injection density are found. The base averaged excess charge carrier injection density increases with higher PERC efficiencies as well as with higher specific resistivity of the base. For a sufficient description of the injection density at open-circuit condition, the law of mass action under applied voltage considering high-level injection can be used to calculate the injection density. At maximum power point voltage, an effective voltage at the pn-junction is derived considering the voltage drop due to the lumped series resistance. This effective voltage is used to calculate an injection density with the law of mass action considering high level injection.
关键词： base resistivity,recombination,PERC solar cells,maximum power point,open-circuit voltage,excess charge carrier injection density
更新于2025-09-11 14:15:04