Efficiency gain in c-Si cells through selective emitter and double printing

Tonini, D.; Bottosso, C.; Cellere, G.; Furin, V.; Galiazzo, M.; Kumar, Prabhat; Tanner, David; Voltan, A.

doi:10.1016/j.egypro.2011.06.189

Cited by 6 publications

(10 citation statements)

References 4 publications

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“…-Dopant paste [11,12] -Silicon inkjet [13,14] -Etch back [15,16] -Etch paste [17] -Masking layer [20,21] -Ion implantation [22,23] -Surface morphology (In this work)…”

Section: Texturization Emitter Doping Passivation Metallizationmentioning

confidence: 99%

“…Second, better surface passivation on the high-sheet-resistance area enhances the short-circuit current density (J SC ) and open-circuit voltage (V OC ) [6][7][8][9][10]. There are several methods to create an SE, such as dopant-paste printing [11,12], inkjet printing [13,14], etch-back [15,16], and laser techniques [17][18][19][20][21][22][23][24]. However, most of these techniques are applied immediately before or after the doping process, so there are risks to the solar cell manufacturing process.…”

Section: Introductionmentioning

confidence: 99%

“…However, most of these techniques are applied immediately before or after the doping process, so there are risks to the solar cell manufacturing process. As shown in Figure 1, SE technologies such as dopant-paste printing and inkjet printing are susceptible to contamination; in other words, there is a risk of contaminants spreading into the silicon during the high-temperature doping process [11][12][13][14]. Etch-back and etch-paste techniques result in the loss of reflectivity due to smoothing of the texture surfaces [15][16][17].…”

Section: Introductionmentioning

confidence: 99%

“…The laser doping method can damage the silicon surface, which is detrimental to the open-circuit voltage (V OC ) [18,19]. In addition, most SE technologies are likely to cause misalignment, which results in over-alignment losses in the alignment with the front electrode during the printing process [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. Recently, as a new technology to overcome this, the development of a new SE to mitigate the recombination loss by the heavily doped epitaxial layer selectively grown after the passivation process, has been reported [24].…”

Section: Introductionmentioning

confidence: 99%

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A Novel Method to Achieve Selective Emitter Using Surface Morphology for PERC Silicon Solar Cells

Park

Cho

et al. 2020

Energies

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Recently, selective emitter (SE) technology has attracted renewed attention in the Si solar cell industry to achieve an improved conversion efficiency of passivated-emitter rear-contact (PERC) cells. In this study, we presented a novel technique for the SE formation by controlling the surface morphology of Si wafers. SEs were formed simultaneously, that is, in a single step for the doping process on different surface morphologies, nano/micro-surfaces, which were formed during the texturing processes; in the same doping process, the nano- and micro-structured areas showed different sheet resistances. In addition, the difference in sheet resistance between the heavily doped and shallow emitters could be controlled from almost 0 to 60 Ω/sq by changing the doping process conditions, pre-deposition and driving time, and temperature. Regarding cell fabrication, wafers simultaneously doped in the same tube were used. The sheet resistance of the homogeneously doped-on standard micro-pyramid surface was approximately 82 Ω/sq, and those of the selectively formed nano/micro-surfaces doped on were on 62 and 82 Ω/sq, respectively. As a result, regarding doped-on selectively formed nano/micro-surfaces, SE cells showed a JSC increase (0.44 mA/cm2) and a fill factor (FF) increase (0.6%) with respect to the homogeneously doped cells on the micro-pyramid surface, resulting in about 0.27% enhanced conversion efficiency.

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“…-Dopant paste [11,12] -Silicon inkjet [13,14] -Etch back [15,16] -Etch paste [17] -Masking layer [20,21] -Ion implantation [22,23] -Surface morphology (In this work)…”

Section: Texturization Emitter Doping Passivation Metallizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A Novel Method to Achieve Selective Emitter Using Surface Morphology for PERC Silicon Solar Cells

Park

Cho

et al. 2020

Energies

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“…A recent study based on the surveying of screen printed 3D microscope line profiles, line segment resistance measurements, electroluminescence (EL) imaging checks for line breaks, and current–voltage (I‐V) measurements, revealed that even when the screen wire diameter and pitch are in accordance with design rules for the finger opening width in the screen, the printed lines (single print) are nevertheless severely non‐uniform when the opening width becomes less than 45 µm, to the extent of causing line breaks to be prevalent throughout the front grid with an accompanying fill factor of 71.1% at an opening width of 30 µm . This finding explains the trend that the industry is adopting double printing as a solution for using screen printing technology to print fine lines, where additional silver paste is printed on top of a first finger print to increase the overall line aspect ratio and uniformity in conductance . Another solution that is compatible with screen printers is the stencil technology .…”

Section: Introductionmentioning

confidence: 99%

Influence of non‐uniform fine lines in silicon solar cell front metal grid design

Wong

Shanmugam

Cunnusamy³

et al. 2015

Progress in Photovoltaics

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While it is well known that the typical printed silver fingers on a silicon solar cell have profile striations, bottle-necks, and line breaks, the impact of these imperfections have not been assessed in calculations of front grid related power losses. This study uses detailed finite element modeling to show that when the realistic effects of non-uniform line conductance is accounted for; the simulated cell efficiency can be significantly lower than under the assumption of uniform lines, becoming closer to measured trends. The study also explores the incorporation of additional interconnecting fingers to the parallel grid finger in the H pattern, concluding that they are typically of no benefit to improving the cell efficiency. As an auxiliary observation, it was found that the efficiency calculated by simple ohmic power loss formulae is typically underestimated by 0.1-0.2% absolute, a margin that should be accounted for in cell optimization and analysis.

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Advanced alignment technique for precise printing over selective emitter in c‐Si solar cells

Voltan¹,

Galiazzo²,

Tonini³

et al. 2011

Progress in Photovoltaics

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Significant improvements in c-Si solar cells performance can be achieved acting on the emitter or on the contact formation side. At the moment, an efficiency gain around 0.5-0.6% abs [1] has been demonstrated for selective emitter (SE) cells, mainly caused by the improvement of the blue response of the shallow emitter. Nevertheless, in case of sub-optimal alignment of the printed metal with the deep emitter, the shallow junction depth leads to a significantly narrower firing process window, consequently causing high contact resistance and poor shunting behavior. Moreover, after Anti Reflective Coating (ARC) the contrast between differently doped areas is poor and often prevents the screen printer vision system from correctly recognizing the pattern for metal printing alignment. Thus, we developed a new equipment, high precision selective emitter, for precise alignment over SE able to guarantee recognition of every SE pattern and consequent printing repeatability within +/-30 mm without rejections or misalignments. In this work, results from experimental investigations and mass production are reported and discussed, including also comparison with standard alignment methods and further feasible applications.New equipment for precise alignment over SE able to guarantee recognition of every SE pattern and consequent printing repeatability within +/-30mm without rejections or misalignments has been developed (examples of SE patterns are reported in the following pictures). Test performed at production sites confirm that an efficiency gain of 0.1% and a significant reduction of rejection can result from the increased robustness of the presented method. Finally, also a correlation between sheet resistance of heavily doped area and image contrast has been demonstrated.

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Efficiency gain in c-Si cells through selective emitter and double printing

Cited by 6 publications

References 4 publications

A Novel Method to Achieve Selective Emitter Using Surface Morphology for PERC Silicon Solar Cells

A Novel Method to Achieve Selective Emitter Using Surface Morphology for PERC Silicon Solar Cells

Influence of non‐uniform fine lines in silicon solar cell front metal grid design

Advanced alignment technique for precise printing over selective emitter in c‐Si solar cells

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