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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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 ...