Berit Schuster | ELANTAS Europe GmbH: Why Is Copper Considered a "Poison" to Silicon, and Can Perovskites Finally Unlock Its Use?

Can Fine-Line Screen Printing Solve the Perovskite-Silicon Tandem Temperature Paradox?

Perovskite-silicon tandem solar cells represent a massive leap in efficiency, but integrating these two distinct semiconductor layers presents severe processing challenges. Unlike traditional silicon photovoltaics that undergo firing processes exceeding 600°C to 700°C, the perovskite top layer is highly sensitive to both temperature and humidity. Metallization must therefore occur under ultra-mild conditions, forcing a hard limit on processing temperatures below 150°C to avoid degrading the active perovskite material.

To achieve high efficiency and minimize shading losses, the conductive grid lines must be incredibly narrow. Screen printing silver-based fingers must move past traditional limits, targeting structures under 30 micrometers—and ideally down to less than 20 micrometers. This requires specialized low-temperature polymer-matrix conductive pastes engineered to retain high electrical conductivity without high-temperature thermal sintering.

These advanced low-temperature screen-printable pastes allow manufacturers to deposit highly conductive, ultrafine structures directly onto fragile solar architectures. The resulting balance between rheology and low-temperature curing offers a pathway to stable, high-efficiency tandem cells while paving the way for flexible, printed electronics outside the PV market.

In this short video, you can learn:
* Why perovskite-silicon tandem cells require processing temperatures strictly below 150°C.
* The technical limits of fine-line screen printing targeting line widths below 20 micrometers.
* How low-temperature polymer-based silver inks bypass traditional 700°C sintering steps.

📋 **Clip Abstract** This clip highlights the processing constraints of perovskite-silicon tandem cells and the need for ultra-low-temperature metallization. It explains how fine-line screen printing can achieve sub-30 micrometer silver fingers without damaging temperature-sensitive layers.

How can functional pastes reduce the number of parts and weight in future cars while enhancing functionality?

The speaker introduces the concept of using functional pastes in printed electronics for mobility applications, particularly in the automotive sector. These pastes, developed by ELANTAS, aim to integrate functionalities within vehicles. The core idea is to reduce the number of electrical parts and overall weight in cars by incorporating printed electronics solutions.

The presentation highlights the increasing complexity of modern vehicles, citing examples like the VW Phaeton with over 11,000 electrical parts and 60 ECUs. The speaker poses the question of how functional pastes can be integrated into future car designs to address the challenges associated with this complexity, such as increased weight and part count. The goal is to leverage printed electronics to provide functionality while minimizing these drawbacks.

The focus is on integrating low-weight functionality with high flexibility, identifying opportunities for functional materials in areas like switches, displays, heaters, and safety detection systems. The speaker emphasizes the potential of printed electronics to contribute to the development of lighter, more efficient, and feature-rich vehicles.

In this short video, you can learn:
* The potential of functional pastes in printed electronics for automotive applications.
* The challenges associated with the increasing complexity of modern vehicles.
* The opportunities for integrating printed electronics to reduce weight and enhance functionality.

📋 **Clip Abstract** The speaker introduces functional pastes for printed electronics in automotive, aiming to reduce part count and weight while enhancing functionality. The clip sets the stage for exploring specific applications and challenges in integrating these materials into future car designs.
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How Does Low-Temperature Curing Impact Contact Resistance in Ultrafine Conductive Lines?

Achieving low contact resistance is one of the steepest hurdles when transitioning from high-temperature co-fired silver pastes to low-temperature alternatives. In traditional solar cell manufacturing, high-temperature firing (typically above 600°C) facilitates direct silver sintering, promoting intimate metallic contact with the silicon emitter layer. In contrast, low-temperature pastes rely on polymer binders that dry or cure at sub-150°C, leaving organic residues that can act as insulating barriers.

When lines are printed with ultrafine widths below 30 micrometers, the contact area shrinks dramatically, compounding the impact of contact resistance on the cell's overall series resistance. The challenge lies in formulating a paste where the metallic particles can establish sufficient percolation networks and interfacial contact without relying on high-temperature thermal sintering.

Recent developmental results show that optimizing the polymer-to-metal ratio and customizing binder chemistry can mitigate this resistive penalty. These novel low-temperature formulations are proving highly promising for tandem cells, demonstrating that the contact resistance penalty can be managed even at line widths approaching micro-scale dimensions.

In this short video, you can learn:
* The distinct differences in contact resistance mechanisms between sintered metallic networks and polymer-matrix conductive pastes.
* Why narrowing printed lines to sub-30 micrometers drastically increases contact resistance challenges.
* Formulation strategies to optimize electrical percolation in low-temperature cured silver inks.

📋 **Clip Abstract** This Q&A discussion addresses the critical challenge of high contact resistance in low-temperature polymer-based silver inks. It explains how fine-line printing amplifies these resistive losses and outlines formulation pathways to overcome them.