Optimization of fine line screen printing using in-depth screen mesh analysis

Ney, Linda; Tepner, Sebastian; Wengenmeyr, Noah; Linse, Michael; Lorenz, Andreas; Bechmann, Sebastian; Weber, Ralf; Pospischil, Maximilian; Clement, Florian

doi:10.1063/1.5125871

Cited by 14 publications

(26 citation statements)

References 9 publications

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“…Afterwards, the shape and exact size of all polygons are calculated, creating a full mathematical description of any screen opening defined by its wire diameter d, the mesh count MC (or wire-to-wire distance d 0 ), the screen opening width w n , and the screen angle φ (illustrated in Figure 2). 22 The simulation approach was experimentally verified in both previous publications. Table 1 shows the range and increment of the sweep for the screen parameters and the alignment on the screen perpendicular to the screen opening direction.…”

Section: Screen Simulation Approachmentioning

confidence: 81%

“…In this study, we utilize the simulation approach first published by Ney et al 22 and then extended by Tepner et al 19 to perform a complete F I G U R E 1 Evolution of published results for the achieved finger width for solar cell metallization since 2005. The figure has been slightly adapted from Lorenz et al 3 and novel results since the original publication are added (see figure legend for details).…”

Section: Screen Simulation Approachmentioning

confidence: 99%

“…3 Additionally, the prediction trend line of the ITRPV 3rd and 10th edition has been added [Colour figure can be viewed at wileyonlinelibrary.com] F I G U R E 2 This SEM image presents a typical screen opening channel. Its geometric architecture is defined by the dimension of the underlying mesh with the wire diameter d and the wire-to-wire distance d 0 , the screen opening width w n , the channel length l, and finally the angle between emulsion edge and mesh φ (commonly referred to as the screen angle φ) 22 screen pattern analysis on different screen openings to derive conclusions about their expected screen printing performance for solar cell metallization. The simulation approach is based on a mathematical model that calculates all intersection points between an arbitrary quadratic grid and a rectangle with the width w n and the length l, which is placed at an angle φ on that grid.…”

Section: Screen Simulation Approachmentioning

confidence: 99%

“…3,[19][20][21] In order to establish a comprehensive understanding of the significance of the presented screen parameters, Ney et al published a method to model the screen opening based on those parameters. 22 Later, Tepner et al expanded this simulation model to derive specific conclusions by simulating and studying the dependency of the wire crossings on such screen parameters. 19 They were able to show that the state-of-the-art method of describing a screen channel by the established parameter open area OA % is not sufficient when fine-line screen printing below 30 μm is desired.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, they introduced a new parameter σ OA , describing the average deviation of OA % across the screen opening length. 22 In this study, we will elaborate on these results by running a full simulation of different screen architectures and then perform solar cell metallization experiments for five different screen architectures at four different screen opening widths w n . Afterwards, the simulation results are directly correlated to the printing performance to create a complete understanding of how changes to the screen architecture are influencing fine-line screen printing.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Screen pattern simulation for an improved front‐side Ag‐electrode metallization of Si‐solar cells

Tepner

Ney

Linse

et al. 2020

Progress in Photovoltaics

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Flatbed screen printing proves to be the dominant metallization approach for mass production of silicon (Si)‐solar cells because of its robust and cost‐effective production capability. However, the ongoing demand of the PV industry to further decrease the width of printed Ag‐electrodes (contact fingers) requires new optimizations. This study presents the latest results on Si‐solar cell metallization using fine‐line screens down to screen opening widths of wn = 15 μm. The best experimental group achieved a record finger geometry with a mean finger width of wf = 19 μm and a mean finger height of hf = 18 μm. Furthermore, solar cell performance using a front‐side grid with a screen opening width of wn = 24 μm is investigated, reporting cell efficiencies up to 22.1% for Passivated Emitter and Rear Contact (PERC) solar cells. Finally, a novel screen pattern simulation is presented, revealing a correlation between the measured lateral finger resistance and the novel dimensionless parameter screen utility index (SUI). It describes the ratio between the average size of individual openings defined by the screen mesh angle and the chosen underlying mesh type. For SUI < 1, the printing result will strongly depend on the screen configuration, whereas for values of SUI > 1, the impact of the screen on the overall printability diminishes.

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Section: Screen Simulation Approachmentioning

confidence: 81%

Section: Screen Simulation Approachmentioning

confidence: 99%

Section: Screen Simulation Approachmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Screen pattern simulation for an improved front‐side Ag‐electrode metallization of Si‐solar cells

Tepner

Ney

Linse

et al. 2020

Progress in Photovoltaics

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The Link between Ag‐Paste Rheology and Screen‐Printed Solar Cell Metallization

Tepner

Wengenmeyr

Linse

et al. 2020

Adv Materials Technologies

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printing machine technology with the goal of continuously increasing production throughput while improving alignment precision. Additionally, further paste development is conducted to enhance printed line geometry and contact formation. Over the last 15 years, screen printing of Ag-pastes for Si-solar cell metallization has become a success story by decreasing the printed electrode width from ≈120 µm in 2007 reported by Mette [2] toward only 20 µm reported by Tepner et al. in 2020. [3] Therefore, flatbed screen printing is catching up with other fine-line printing approaches for solar cell metallization. Recent studies reported finger widths down to 17 µm by using the parallel dispensing approach [4] and 20 µm by using pattern transfer printing. [5] Both results demonstrated homogenous line widths at competitive printing speeds. These achievements of screen printing have their origin in the continuous efforts of the industry around metallization to improve their technology and products and the scientific community providing an in-depth insight into the underlying physics around that topic. Over the years, the latter provided various research studies, focusing on understanding the impact of paste rheology, [6-10] optimizing the electrical performance of Ag-contacts, [11-14] and the impact of screen design on printing results. [6,15-19] Commonly available Ag-pastes for front-side PERC are highly filled suspensions containing up to 95 wt% spherical Ag-particles with diameters below 5 µm. [2,20] They show non-Newtonian flow characteristics with strong shear thinning behavior after exhibiting significant yield stress. [21,22] A fast and reproducible screen printing process imposes a few crucial requirements on the rheology because the paste is first excessively sheared when being transferred through a fine mesh. [23] Afterward, it is further pushed onto the substrate through the screen opening width w n and the height EOM (emulsion over mesh). During this motion, shearing should already be minimized because the recovery of the zero shear viscosity is highly time-dependent (thixotropic behavior). [6,24] Usually, this minimization of shearing within the screen opening is achieved by the paste's ability to slip at the emulsion surface. This effect has been the focus of several research studies, which showed how slip effects are enhancing screen-printing performance. [25-27] After the paste has been pushed through the screen opening onto the substrate, the Today's photovoltaic production chain is moving into a material crisis as the use of silver for front-side metallization of passivated emitter and rear contact solar cells remains a crucial requirement. The shared effort of the scientific and industrial community to further reduce Ag-consumption as much as possible without compromising cell efficiency has become more challenging in recent years. Further improvements require a deep understanding on the paste-screen interaction at narrow line widths. This study presents the impact of Ag-paste rheology on fine line screen ...

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Prediction of Screen‐Printed Electrodes with Fine‐Line and Arbitrary Structures

Singler,

Ney,

Auerbach

et al. 2024

Energy Tech

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Currently, the photovoltaic manufacturing industry is confronted with an upcoming material shortage, primarily driven by the continued dependence on silver for front‐side metallization in TOPCon, SHJ, and PERC solar cells. This study employs a mathematical model originally introduced by Ney et al. in 2019 to predict the outcome of printed contact structures based on mesh characteristics. For validation, printing experiments are conducted with variations in printing speed, screen angle, and calendaring strength. It is generally observed that predictions for screens with a 20° mesh angle are less accurate than for other angles. In addition, it is noted that the prediction became more accurate with increasing channel width. Although, for some cases, a prediction accuracy between 77 and 87% is achieved, it is important to acknowledge that the results obtained from the simulation deviate from the real‐world observations to some extent. Additionally, a clear correlation between mesh thickness and printed volume is observed, enabling the prediction of silver usage and potential material savings.

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Optimization of fine line screen printing using in-depth screen mesh analysis

Cited by 14 publications

References 9 publications

Screen pattern simulation for an improved front‐side Ag‐electrode metallization of Si‐solar cells

Screen pattern simulation for an improved front‐side Ag‐electrode metallization of Si‐solar cells

The Link between Ag‐Paste Rheology and Screen‐Printed Solar Cell Metallization

Prediction of Screen‐Printed Electrodes with Fine‐Line and Arbitrary Structures

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