Analysis of contact recombination at rear local back surface field via boron laser doping and screen-printed aluminum metallization on p-type PERC solar cells

Tomizawa, Yuka; Ikeda, Yuichi; Itoh, Haruhiko; Takano, Shiro; Löffler, J.; Manshanden, P.; Romijn, I.G.

doi:10.1016/j.egypro.2017.09.256

Cited by 11 publications

(1 citation statement)

References 15 publications

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“…In these solar cells, metal-semiconductor (MS) contacts are made on the heavily doped Si regions. This results in high recombination current densities at the metalized areas (J0,metal), which range from about a few hundred to a few thousand fA/cm 2 depending on the cell technology [5][6][7][8]. The high J0,total caused by a full-area rear MS contact in Al-BSF solar cells is addressed by implementing local contact structures in the PERC [9] and PERT [10] cells.…”

Section: Introductionmentioning

confidence: 99%

Thermal stability improvement of metal oxide-based contacts for silicon heterojunction solar cells

Cho

Radhakrishnan

Sharma

et al. 2020

Solar Energy Materials and Solar Cells

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Metal oxides are interesting materials for use as carrier-selective contacts for the fabrication of doping-free silicon solar cells. In particular, MoOx and TiOx have been successfully used as hole and electron selective contacts in silicon solar cells, respectively. However, it is of paramount importance that good thermal stability is achieved in such contacts. In our work, we combined i-a-Si:H/MoOx based hole contacts with electron contacts featuring i-a-Si:H/TiOx/low work function metal (ATOM) to fabricate doping-free cells, termed MolyATOM cells. We found that the thermal stability of the ATOM contact was improved when the i-a-Si:H was annealed (300 °C for 20 min in N2) before depositing TiOx (i.e. pre-TiOx annealing), which reduces the hydrogen content in i-a-Si:H by about 27 %rel, and thereby the H-related degradation of the ATOM contact characteristics. Moreover, it was found that reducing the thickness of the low-work function metal on top of the TiOx enhanced the thermal stability of the ATOM contact. With these adaptations, the MolyATOM cell efficiency was improved by 3.5 %abs, with the highest efficiency of 17.6 %. Moreover, the cells show improved thermal stability after the above-mentioned pre-TiOx annealing, which is confirmed by annealing tests at cell level as well as damp-heat tests at module level. The insights of this study could be used to tailor other metal-oxide based electron or hole contacts.

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Section: Introductionmentioning

confidence: 99%

Thermal stability improvement of metal oxide-based contacts for silicon heterojunction solar cells

Cho

Radhakrishnan

Sharma

et al. 2020

Solar Energy Materials and Solar Cells

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Printing technologies for silicon solar cell metallization: A comprehensive review

Tepner

Lorenz

2023

Progress in Photovoltaics

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This paper presents a comprehensive overview on printing technologies for metallization of solar cells. Throughout the last 30 years, flatbed screen printing has established itself as the predominant metallization process for the mass production of silicon solar cells. For this reason, we will provide a detailed review on its history, its evolution over time, and how the continuous efforts of the scientific and industrial community for further improvements revolutionized the entire PV industry. Furthermore, we will guide the reader through the physics on silicon solar cell metallization, the fundamentals on contact formation, and what type of challenges and requirements these topics create for printing technologies. The main topic of this review addresses the flatbed screen-printing process mechanics, its different process sequences, corresponding screen technology, and the very important impact of paste rheology on the printing result. Finally, we will compare alternative upcoming printing approaches to flatbed screen printing and discuss how they might solve upcoming challenges in metallization in terms of increasing the throughput rates at an everdecreasing grid line width and reduced silver consumption.

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Improved Bifacial Properties of P‐Type Passivated Emitter and Rear Cell Solar Cells toward High Mass Production Efficiency

Wang

Chen³

et al. 2021

Physica Status Solidi (a)

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Passivated emitter and rear cell (PERC) has shifted to mass production and achieved great success in the past few years. [1][2][3] In comparison with aluminum back surface field (Al-BSF)-type solar cells, the rear-side surface recombination is significantly reduced by introducing a passivation layer between silicon substrate and electrodes, which can boost both open-circuit voltage and short-circuit current. [4] Later, the average industrial conversion efficiency of p-type mono-silicon PERC has achieved 22.5-22.8% and even beyond 23% for few leading photovoltaic manufacturers, with the continuously evolving optimizations in industrialization technology, e.g., emitter doping optimization, [5,6] laser-doped selective emitter, [7,8] front surface anti-reflection and passivation, [9][10][11] and reduced shading loss and electrode contact. [12,13] Longi solar has released the world record R&D efficiency of 24.06% on a commercial-sized PERC, [14] which means there still exists a gap of %1% absolute in conversion efficiency moving from laboratory R&D efficiency toward mass production efficiency.An effective solution to further enhance the power generation capacity is the employment of a bifacial PERC structure. The bifacial PERC and module have the potential to absorb the scattered and reflected light on the back of the solar module, which can boost the module power output up to 30% and lower the levelized cost of electricity (LCOE). [15][16][17] However, the bifacility of p-type PERC is lower than that of other high-efficiency concepts, such as tunnel oxide passivated contact (TOPCon) and silicon heterojunction (SHJ) solar cell, limited by its obviously decreased short-circuit current at the rear side. Dullweber et al. first presented the novel bifacial PERC design by screen printing rear-side aluminum (Al) fingers instead of full-area Al-BSF, with a bifaciality of 79.3%, [18] and pioneered the bifacial application of PERC solar cells. The influence of rear-side morphology effects the passivation property significantly. A smooth rear surface is preferred to obtain high open-circuit voltage, [19,20] but suffers from rear-side light trapping limitation. One has to balance the rear passivation and photon absorption. Meanwhile, the deposition of a high-quality rear passivation film also helps the improvement of rear-side efficiency. The Al 2 O 3 film, SiO 2 film, SiN x film, and their stack layers have been studied to provide both excellent hydrogen passivation and chemical

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Analysis of contact recombination at rear local back surface field via boron laser doping and screen-printed aluminum metallization on p-type PERC solar cells

Cited by 11 publications

References 15 publications

Thermal stability improvement of metal oxide-based contacts for silicon heterojunction solar cells

Thermal stability improvement of metal oxide-based contacts for silicon heterojunction solar cells

Printing technologies for silicon solar cell metallization: A comprehensive review

Improved Bifacial Properties of P‐Type Passivated Emitter and Rear Cell Solar Cells toward High Mass Production Efficiency

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