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 ...

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Flatbed screen printing is the dominating process in industry for metallization of silicon solar cells. It offers high throughput rates, high flexibility of printing pattern, and an overall very cost-effective production compared with other printing technologies. However, the ongoing demand for an optimization of printed silver electrode shape creates an increasing challenge to paste and screen development. The recent trend of so called "knotless" screens with a screen angle of 0°offers an increased paste transfer, therefore, better electrode conductivity, which leads to an improved solar cell efficiency. The disadvantage of this screen architecture is a reduced screen lifetime and low production yield. This article presents a systematic simulation of screen pattern to investigate screen angles, which allow for an improved knotless screen architecture. Therefore, different types of wire crossings have been defined, simulated, and experimentally verified by microscope images. For example, when 14.036°, 18.435°, and 26.565°a re used, knotless screen pattern openings emerge without showing any of the disadvantages of regular 0°-knotless screens. For this reason, statistical screen lifetime estimations are carried out by modeling the intersection lengths of all mesh wires and the emulsion edge across the screen opening. Furthermore, a detailed analysis on manufacturing tolerances is given, showing that the 26.565°s creen angle offers the best compromise between challenges during manufacturing and potential performance in production of Si-solar cells.

This article presents the application of a parallel dispensing device for low‐temperature silver paste metallization on transparent conductive oxide (TCO) layers of Cu(In1 − xGax)Se2 (CIGS) substrates as an alternative metallization technology to screen printing and inkjet printing. A curing variation experiment is performed to analyze the effect of different curing conditions on the resulting contact resistivity of the metal grid. Contact resistivity values below 5 mΩcm2 are achieved. Furthermore, CIGS mini‐modules are metallized with three different low‐temperature paste formulations obtaining a record core finger geometry of 25 μm and an average optical aspect ratio of 0.46 using 25 μm nozzle openings. The dispensed metal grid on the TCO layers achieves the comparable current density values of jsc = 32.2 mA cm−2 and the open‐circuit voltages values per cell of Voc = 672 mV as the screen printed metal grid on CIGS mini‐modules and, hence, a nominal power of 2.05 W. The metal grid enables the use of broader cell widths compared with grid‐free CIGS samples and results in a reduced dead area.