Fraunhofer Lighthouse Project »MaNiTU«

To successfully combat climate change, a transformation of the current energy system and a massive expansion of photovoltaics (PV) is necessary. Many studies show that photovoltaics will become the most important energy technology worldwide. It is therefore crucial for Europe and Germany to be active in this technology field and to serve the gigantic market with new disruptive innovations. The currently dominant silicon solar cell technology is largely based on innovations from Europe, Japan and the USA. Accordingly, European equipment manufacturing and material supply for silicon technology is still globally significant. On the other hand, silicon solar cells have recently been manufactured mainly in Asia. However, the further technological development of the silicon solar cell will reach its physical limit in the next few years. Thus, the development of new and innovative technologies offers Germany the opportunity to regain an international top position in the production of solar cells in addition to research, plant engineering and material supply. 

This is where the MaNiTU lighthouse project comes in: By developing sustainable, highly efficient and cost-effective tandem solar cells based on perovskite absorber materials, MaNiTU opens up an outstanding opportunity for a successful European manufacturing PV industry:

• Reduction of area-dependent costs and lowering of the electricity production costs
• Enabling a broad field of applications from classic PV systems to integrated applications on buildings or in vehicles 
• Reduction of resource consumption and the associated significant material flows of a global PV market on the terawatt (TW) scale. 
• Avoidance of critical materials and development of recycling concepts. 

Emerging perovskite solar cells have been developing rapidly in research since 2009, with an efficiency increase from 3.8% to over 25% today. Based on known perovskite absorbers, new absorbers as well as contact and passivation layers matched to them for highly efficient perovskite-based tandem solar cells are therefore being developed in MaNiTU using state-of-the-art material science methods. From the very beginning, the material and process development is analyzed and evaluated by comprehensive sustainability assessment.

The innovative approach of closely integrating theoretical modeling and experimental work on absorbers and contact layers makes it possible to understand interface effects and use them specifically for desired functionalities. At the end of the project, stability and high efficiencies will be demonstrated at module level, and the necessary material combinations and manufacturing processes will be secured by patents. In addition, a significant increase in knowledge regarding absorber materials and interface effects is expected. The developed materials and processes as well as the gained knowledge are additionally relevant for other optoelectronic devices and applications. 

Further development of sustainable absorber materials

The success of perovskite solar cells has shown that it is possible to find entirely new material systems that can continue to advance the technological development of photovoltaics in the long term. The current perovskite materials should therefore not be regarded as the end point of absorber development. Instead, it is important to continue the development in a targeted manner in order to have an absorber material available that is stable over the long term, cost-effective and can be produced with a good environmental balance from materials that are also available on a TW scale.

Efficiency increases and simultaneous cost reduction with the help of tandem solar cells

In addition, development should focus on the realization of tandem solar cells. In tandem solar cells, specially adapted materials enable the different spectral ranges of sunlight to be used in different optimized sub-cells. This significantly increases the efficiency of the overall solar cell. Since most of the costs of a photovoltaic system scale with the area, such an increase in efficiency means a strong lever for lower electricity production costs. In addition, resource efficiency, in particular material and land consumption, is decisively improved by higher efficiencies.

With efficiencies on a laboratory scale of over 26.6 % and an annual increase in efficiency of 0.5 %abs in industrial production, the physical barrier of 29.4 % for silicon technology is already very close. In contrast, silicon-based tandem solar cells promise efficiencies of more than 35 % and at the same time make it possible to continue the use of the existing know-how and production facilities of silicon technology. In the medium term, the silicon sub-cell can also be replaced by a new absorber material, enabling consistently cost-effective thin-film production. The MaNiTU project aims to find and develop the material systems required for this. 

Security of supply and competitiveness

By focusing on as yet unknown materials, there is an opportunity to generate a significant know-how and IP advantage in the field of tandem solar cells. MaNiTU thus lays the foundation for expanding Germany's leading position in tandem technology, establishing new value chains in Germany and opening up new markets. Due to the enormous global market, there is also a high export potential.

In view of the importance of photovoltaics for the German and European energy supply, the development of a European PV industry is at the same time an essential contribution to security of supply and to ensuring long-term competitiveness and innovation.

Environmental and climate compatibility

Focusing on the realization of highly efficient solar cells while taking into account the environmental and climate footprint of the used materials, enables sustainable technological development. Early consideration of recycling concepts of the newly developed tandem solar cells in the context of a circular economy is also being developed. MaNiTU therefore contributes to all three dimensions of the energy policy target triangle. In addition, for the materials to be developed, the corresponding production technologies and findings in the field of material science and interface properties, relevant utilization possibilities are alsoexpected beyond the applications in tandem solar cells.