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Analysis of different conductive pastes to form the contact with the boron back surface field in PERT silicon solar cells
摘要： The industrial production of solar cells of the PERC family is growing, because the potential to increase the efficiency due to the passivation of the rear face. The PERT solar cell is a cost-effective structure of the PERC configurations. The goal of this paper is to analyze the influence in the electrical parameters of different metal pastes used to form the contact with the boron back surface field of PERT solar cells passivated with silicon dioxide on both sides and developed with a cost-effective process. The boron doped BSF and phosphorus emitter were carried out with reduction of steps. Solar cells were processed with three different conductive pastes: (1) an aluminum paste (PV381), (2) a silver/aluminum paste (PV3N1) and (3) a silver paste (PV51G), with different viscosity and solids content. The pastes were produced by DuPont. The PV381 and PV3N1 pastes produced solar cells with the efficiency of 16.2% and 15.9%, respectively. The higher open circuit voltage was achieved with the aluminum paste, indicating that this paste is more effective to produce the selective back surface field. The PV51G paste is not suitable to form the rear contact.
关键词： aluminum and silver/aluminum pastes,boron back surface field,PERT silicon solar cells
更新于2025-09-23 15:19:57
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Ultra-Thin Lightweight Bendable Crystalline Si Solar Cells for Solar Vehicles
摘要： Komatsu NTC developed ultra-thin wafer slicing with low kerf-loss by multi diamond-wire saw. We modified slicing conditions and diamond-wire specifications to keep the straightness of wire for the fine pitch slicing and established 150 μm pitch slicing technology. The as-cut wafer thickness is 90 μm, and the kerf-loss is 60 μm. As a result, the highly flexible ultra-thin wafer can be obtained with well-controlled surface crystallinity. The PERT cell fabrication trial using ultra-thin wafers showed that the relative deference of cell efficiency between 166 μm thick and 84 μm thick solar cells was just only 1.2%.
关键词： thin wafer,PERT,slice,crystalline Si
更新于2025-09-19 17:13:59
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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) - Gettering efficacy of an APCVD glasses based stacked co-diffusion for bifacial mc-Si PERT solar cells
摘要： Gettering of impurities is an important task in p-type mc-Si solar cell production. Phosphorus diffusion via POCl3 is currently the most common way to achieve this. We report about the gettering efficacy of a co-diffusion in which POCl3 is not used. Phosphorus and boron containing glasses are both deposited prior to the diffusion via atmospheric pressure chemical vapor deposition (APCVD). The presented APCVD glasses based co-diffusion allows a loading without spacing and therefore has the potential for a very high throughput. As we demonstrate in this work, the overall gettering efficacy in different kinds of stacks is similar to the gettering efficacy in non-stacked APCVD glasses based diffusions. The reduction of interstitial iron in the analyzed lifetime samples is ascribed to phosphorus diffusion gettering and works in stacks just as well.
关键词： co-diffusion,Gettering,PERT solar cells,APCVD,mc-Si
更新于2025-09-16 10:30:52
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Investigation on Industrial Screen-Printed Aluminum Point Contact and Its Application in n-PERT Rear Junction Solar Cells
摘要： As compared with the traditional back surface field (BSF) solar cells, the n-type passivated emitter rear and totally diffused rear-junction (n-PERT-RJ) solar cells have much lower carrier recombination losses on their rear sides. In order to obtain more benefits (higher open-circuit voltages) from the currently passivated rear sides, the implementation of the point contact concept is an intuitive solution. In this article, we present industrial screen-printed point contacts that are metallized with aluminum (Al) pastes containing silicon additives (Si-add). To understand the impacts of the Si-add on the performance our n-PERT-RJ solar cells, the detailed loss analysis on the open-circuit voltage (VOC), short-circuit current density (JSC), and fill factor are performed separately. The effect of Si-add and pitch of laser contact openings (LCO) on the point contact characteristics are also investigated. In the last part, we introduce an innovative “point-line” contact concept on the rear side, which is composed of dot-shaped LCO and Al metal finger design, resulting in an n-PERT-RJ solar cell to reach VOC of 692 mV and peak efficiency of 22%. The 60% bifaciality of the device opens the way for an additional power output on module level, which further reduces the levelized cost of electricity. These features make the rear-side point contact design more flexible to be applied in industrial mass production.
关键词： laser contact opening (LCO),levelized cost of electricity,Aluminum (Al) paste,n-type passivated emitter rear and totally diffused (n-PERT),bifaciality,silicon solar cell,industrial,point contacts,screen printed,n-type,rear junction
更新于2025-09-16 10:30:52
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Effect of Oxygen Precipitation in Silicon Wafer on Electrical Characteristics of Fully Ion-Implanted n-Type PERT Solar Cells
摘要： Fully ion-implanted n-type PERT solar cells with boron-implanted emitter and phosphorus-implanted back surface field were fabricated on the n-type silicon wafers obtained from the top part of the magnetic field-applied Czochralski ingot. It was observed that the electrical parameters are widely dispersed; among 11 solar cells, the best performing achieved 20.4% front side conversion efficiency, whereas the worst achieved 19.0%. Although the silicon wafers had low oxygen concentrations of 3–4 × 1017 atoms/cm3, the density of oxygen precipitates in the silicon wafers was on the order of 109 /cm3 as a consequence of the fully ion-implanted n-type PERT silicon solar cell processes. In addition, it was observed that the front side conversion efficiencies of the solar cells depended on the density of oxygen precipitates. Furthermore, the behavior of the oxygen precipitation during the fabrication processes of the solar cell is discussed.
关键词： oxygen precipitation,conversion efficiency,ion implantation,n-type PERT solar cells,silicon wafers
更新于2025-09-12 10:27:22
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Comparative Analyses Between Two Techniques To Understand Metal-Induced Recombination Losses In Industrial N-Type Bifacial PERT Solar Cells
摘要： Due to the high cell efficiency, low Light-Induced Degradation (LID) and high bifaciality, n-type bifacial passivated emitter and rear totally diffused (PERT) solar cells are being widely researched and currently being implemented in mass production. With the improvement of dopant profiles and passivation quality, J0,emitter and J0,bsf under passivation area could reduce to lower values. However, the Voc of cell is still not high enough which may be caused by the high recombination loss under metal area. In this paper, two different methods which are suitable for low cell efficiency diagnoses are investigated and compared to evaluate the J0,metal on both boron and phosphorus doping side of solar cells. For the first method, high resistivity n-type mono wafers are prepared with double front side or rear side structure of solar cell. Four different types of metallization ratio areas are designed on the one wafer of single side. By testing the J0,total of these four area, we can fit a line of J0,total with different contact fraction, so the J0,metal can be calculated by the expression of J0,total, J0,passivation and contact fraction. For the second method, Suns-Voc and Suns-PL are used for calculation. Four types of cell structures with metal, without metal, only with front metal and only with rear metal are fabricated to measure the probed Voc and PL derived Voc either use (i) different carrier injection levels or (ii) different light illuminations. A line can be fitted under different Suns, and by contrasting the line of cell structure and other structures, J0,metal of front metal and rear metal can be calculated by the bias of these lines. By comparing this two methods, we get the boron side Ag/Al paste J0,metal and the phosphorus side Ag paste J0,metal are around 2801 fA/cm2 and 964.9 fA/cm2, respectively. By comparing this two methods, the value of second method is lower than the first method and more appropriate for IV simulation using Quokka.
关键词： Bifacial,PERT solar cell,Suns-PL,QSSPC,Suns-Voc,J0,metal
更新于2025-09-12 10:27:22
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Investigation of dielectric layers laser ablation mechanism on n-PERT silicon solar cells for (Ni) plating process: Laser impact on surface morphology, composition, electrical properties and metallization quality
摘要： Laser contact opening is a critical step for solar cells manufacturing and needs to be optimized to achieve high efficiencies. In this paper, laser contact opening using a picosecond laser (wavelength 355 nm, pulse duration 10 ps) has been carried out on n-PERT precursors composed of a SiOx/SiOxNy stack on the rear polished side and a SiOxNy layer on the front textured side. By varying peak fluence from 0.130 J/cm2 to 2.159 J/cm2 and spot overlapping, ninety parameters combinations have been tested to open these dielectric layers. Surface morphology characterization, before and after laser ablation, has been realized using Confocal Laser Scanning Microscopy and Scanning Electron Microscopy. Bulk and surface compositions have also been investigated by Energy Dispersive Spectroscopy and X-ray Photoelectron Spectroscopy analysis, respectively. Results have shown the existence of four separated laser impacted areas on the polished side and a related ablation mechanism is suggested. Also, electrical characterization using four probe measurements and calibrated lifetime photoluminescence revealed that electrical properties of the silicon underlying increased when post laser annealing was performed associated with no spot overlapping. Then, nickel electroless deposition has been performed and first characterizations indicate adherence issues and inhomogeneous metallization. Characterization of metallized samples revealed that these observations were closely linked to the non-homogenous surface morphology and composition after laser ablation.
关键词： Ni plating,Surface damages,n-PERT cell,Ablation mechanism,UV-Picosecond laser
更新于2025-09-12 10:27:22
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High-efficiency n-type silicon PERT bifacial solar cells with selective emitters and poly-Si based passivating contacts
摘要： Bifacial crystalline silicon (c-Si) solar cells have currently attracted much attention due to the front high-efficiency and additional gain of power generation from the back side. Here, we have presented n-type passivated emitter and rear totally-diffused (n-PERT) bifacial c-Si solar cells featuring front selective emitter (SE) and polysilicon (poly-Si) based passivating contacts. The SE formation was scanned with laser doping based on front boron-diffusion p+ emitter. The poly-Si based passivating contacts consisting of nano-layer SiOx of ~1.5 nm thickness grown with cost-effective nitric acid oxidation and phosphorus-doped polysilicon exhibited excellent passivation for high open-circuit voltage. We have successfully achieved the large-area (156 × 156 mm2) n-PERT bifacial solar cells yielding top efficiency of 21.15%, together with a promising short-circuit current density of 40.40 mA/cm2. Theoretical calculation has further demonstrated that the optimal thickness of SiOx nano-layer will increase from 1.5 nm to 1.8 nm if the density of interface defect state decreases by one magnitude from 1 × 1010 cm?2/eV, and the cell efficiency can be improved up to 24.64% with open-circuit voltage over 0.720 V by optimizing the parameters of functional materials and interface layers. The present work has indicated that the commercialization of low-cost and high-efficiency n-PERT bifacial c-Si cells is possible due to the processes compatible with existing production lines.
关键词： n-PERT bifacial,Nano-layer SiOx,Poly-Si based passivating contacts,c-Si solar cells,Selective emitter
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) - Fine line Al printing on narrow point contact opening for front side metallization
摘要： Aluminum (Al) screen-printed narrow fingers on textured passivated emitter and rear totally diffused (n-PERT) front junction Si solar cells are applied and investigated. Commercial Al paste is screen-printed on symmetric test structures with different Local Contact Opening (LCO) designs by varying the dot-to-dot distances and finger widths. Strong dependency of the metal-silicon saturation current density (J0-met) is found for the considered geometries. Narrow Al grid metallization induced emitter recombination current density can be decreased by optimizing the dot-dot distance. Best results of our test matrix were determined for an 80 μm dot-dot pitch, realizing J0-met values down to 649 fA/cm2 when using narrow fingers of 65 μm compared with the J0-met of 1100 fA/cm2 identified for a commercial Ag/Al paste. For dot-to-dot distances below 40 μm, common pattern of bifacial p-type PERC, fingers with widths exceeding 120 μm are needed to realize J0-met values below 400 fA/cm2. Additionally, the shape and size of the Al-Si alloy and p++ doping layer depth after firing are strongly affected by the combination of dot-to-dot distances and screen-printed finger widths.
关键词： point contact,Al,contact formation,n-type,n-PERT,screen printing,boron emitter
更新于2025-09-11 14:15:04