Flexographic printing goes electronic: Solar cells are just the beginning

ContiTech and the Fraunhofer Institute for Solar Energy Systems have developed an innovative solution that will drastically cut the cost of producing solar cells. It’s a technological advance that could restore Germany’s global competitiveness in this segment.

Flexographic printing goes electronicFrom left to right: Björn Heise, application engineer at ContiTech Elastomer Coatings, and production worker Torsten Raschdorf check the fine structures of a flexographic printing plate carved out with high-tech lasers.
Interactive business cards with QR codes, speaking product packages, E-readers with books on demand, displays and fridge magnets with Bluetooth sensors and memory chips that automatically write your shopping list for you… Printed electronics are set to make many a wish a cost-efficient, user-friendly reality. The potential of this niche technology has long been recognised in industry, where drivers of innovation embarked on the next step some time ago. Printing is – and will remain – an extremely demanding and sophisticated production technology and is constantly being enhanced and improved. Right now innovators are combining it with electronic components. In conjunction with the Fraunhofer Institute for Solar Energy Systems and various other partners, ContiTech has developed an innovative solution that will drastically cut the cost of producing solar cells and presents a prototype solar cell that had been manufactured by means of flexographic printing.  
Flexographic printing goes electronicDorothea Bunzendahl, Area Manager at ContiTech Elastomer Coatings in Northeim, is one of the seven-strong team driving development in functional printing.​

With this product we’re killing at least two birds with one stone,” said Amin Senne, Flexo Business Manager with ContiTech, as he presented one of his prototypes. “First of all, it drastically reduces the cost of mass-producing solar cells. Secondly, because of that, it will help make Germany more competitive, as it is up against so many other countries that produce more cheaply.”

Rather than using classic printing inks, this latest technique relies on organic or polymerbased printing fluids. These come in paste form and conduct electricity. They are “printed” onto a substrate, which might consist of paper, foil, textile or silicon wafer, for example (the latter being a circular or square plate about 1 mm thick of the base material for electronic building blocks).

Part real, part vision

“This innovative technology is just the very beginning of a development that will take ContiTech forwards in the future. In line with our guiding principle, Engineering Next Level, we want to explore new fields of application for it and enter into them quickly. Our research into printing crystalline substances and organic solar cells is still ongoing because we want to find out how to make them flexible and bendy,” Senne explains. Because it has such a diverse range of applications, this new production technique is opening up growth opportunities in a variety of different industry sectors.

Flexographic printing goes electronicHigh cost-cutting potential: Armin Senne, Flexo Business Manager at ContiTech Elastomer Coatings, presents the prototype of a printed solar cell.​

During the course of its research, ContiTech has been able to enhance micro-structured elastomer print plates to transfer metal fluids onto substrates – and found out in the process that flexographic printing could potentially cut the cost of producing crystalline solar cells significantly. The same technique also has the capacity to speed up manufacturing, allowing cells to be produced more swiftly than by conventional screenprinting methods.

In book, newsprint or image printing, maximum resolution of printed structures depends on the human eye. Structures of less than 20 micrometres – the average human hair is 10 micrometres – are not perceptible to humans. Moreover, with conventional printing methods they are impossible to achieve. But as long as errors, such as gaps, remain invisible to the observer, they will go unnoticed.

In the field of electronics, however, shortcomings of this kind are far less easily forgiven. Here, fine structures are a sign of quality – but also essential when it comes to ensuring the functionality of printed components. That’s why ContiTech uses laser tools to give flexographic printing plates the structures they need. And the result is indeed impressive: With print resolutions of 2540 -5080 dpi, even superfine lines can be printed flexographically. Moreover, in the case of solar cells, this method of printing helps reduce shadowing on the front of the cell, which in turn enhances efficiency. What’s more, the more effective the solar cell, the more energy the photovoltaic cell releases for conversion into electricity.

Laser engraving and elastomer pave the way for new markets and products

With its high-tech elastomers and laser engraving, ContiTech is laying the foundation not only for possible applications in printed electronics but also for innovative approaches to completely new product lines. Combined with laser technology, the physical and chemical properties of elastomers are paving the way for three-dimensional elastomer processing, for instance, and consequently the three-dimensional forming of products.

At the Hannover Messe, you will learn more about the latest developments in the field of functional printing at ContiTech’s booth F18 in hall 6.

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