Perovskite Thin-Film Photovoltaics

Perovskite-based photoabsorbers have a low material criticality, a high light absorption capacity and can achieve specific optical properties by adjusting the chemical composition. This makes perovskites interesting for use in multi-junction solar cells: by stacking several perovskite solar cells with different band gaps, the efficiency can be significantly increased and exceed the theoretical maximum of single-junction solar cells. 

In the "Perovskite Thin-Film Photovoltaics" research topic, we are working on the development of scalable manufacturing processes for perovskite solar cells and modules. The focus here is on low-temperature processes in which functional layers are deposited or printed from solution. This makes it possible to produce the components on flexible substrates in order to open up new fields of application - particularly in the area of integrated photovoltaics. We conduct our research at an international level and are a point of contact for industrial and academic players in the field of coating technology, cell production and system integration.

• Material Screening and Cell Stack Optimization of Perovskite Thin-Film Solar Cells
• Graphite-Based Electrodes for Perovskite Solar Cells
• Perovskite-Perovskite Tandem Photovoltaics
• Module and Production Processes for Perovskite Thin-Film Photovoltaics
• Long-Term Stability of Perovskite Thin-Film Solar Cells
• Characterization and Modeling of Perovskite Thin-Film Solar Cells

Novel perovskite semiconductors, as well as inorganic and organic contact materials, are continuously being synthesized worldwide. This makes it essential to screen current promising materials on an ongoing basis. Our focus is not only on achieving the highest efficiencies, but also on long-term stability and compatibility with production-relevant cell stacks and processes. The most suitable materials are identified for various applications.

Our R&D Services on this Topic Include:

• Testing of materials and components for use in perovskite solar cells
• Benchmarking in reference cell stacks
• Development of production-relevant cell concepts

As an alternative to metal electrodes, we are investigating the use of graphitic carbon as a back contact in perovskite solar cells. The carbon electrodes can be used in highly efficient solar cell stacks by coating or printing processes, thus enabling access to fully printed solar cells. This reduces the use of high-temperature or vacuum processes, which contributes to a lower carbon footprint of the solar cells. Furthermore, since perovskite solar cells with carbon electrodes have shown better stability compared to solar cells with metal electrodes, there is the potential to enable fully printed PSCs with both the highest efficiencies and the highest operational stability.

Our R&D Services on this Topic Include:

• Development of scalable coating and printing processes
• Investigation of the compatibility of paste formulations with perovskite solar cell stacks
• Development of novel processes for laminating electrodes

The band gaps and thus the absorption properties of perovskite semiconductor materials can be easily adjusted by adapting the chemical composition. For photovoltaic applications, we are investigating materials that can be combined in perovskite-perovskite tandem solar cell architectures to exceed the efficiency limit of single solar cells. At the same time, we are developing scalable processes for the production of demonstrator modules.

Our R&D Services on this Topic Include:

• Screening and benchmarking of functional materials for contact and passivation layers
• Cell architectures without rare materials for recombination layers and electrodes
• Production of perovskite-perovskite tandem modules

We can produce perovskite thin-film PV modules using various coating processes, in air and under inert gas, on both rigid and flexible substrates. Key aspects of the developments are scalable processes using cost-effective and harmless materials. Cell stacks, interconnection concepts and dimensions are specifically optimized depending on the application. For example, optimal modules for indoor lighting applications differ significantly from those that are to be used outdoors. The choice of perovskite absorber with regard to the band gap, the electrode layers and the module layout depend on these practical differences.

Our R&D Services on this Topic Include:

• Application-specific optimization of the module layout
• Development of cost-effective and robust module concepts
• Production of demonstrator modules

The requirements for long-term stability and key influencing factors depend heavily on the target application. Various ageing tests under controlled conditions (e.g. continuous illumination with simulated sunlight or LEDs, increased temperature) and outdoors can identify the decisive factors in each case and improve the perovskite solar cells and modules in a targeted manner. From small laboratory cells to modules, we can precisely determine the long-term stability by measuring characteristic curves and maximum power point tracking. By recording important environmental parameters, correlations can be established and the behavior at different light intensities, angles of incidence and temperatures can be determined. By determining such data and in-depth characterization, the decisive factors for degradation can be identified and the component stability of perovskite PV can be improved.

Our R&D Services on this Topic Include:

• Accelerated ageing in the laboratory
• Outdoor weathering on a roof test stand
• Standard tests in an accredited test laboratory

An in-depth understanding of how perovskite solar cells work is crucial for the efficient further development of the technology in the long term. A broad spectrum of characterization methods makes it possible to identify specific limiting factors. Modeling makes it possible to quantitatively test hypotheses on influencing mechanisms and thus gain an increasingly detailed understanding. These methods also help in the area of long-term stability, both to localize weak points in the encapsulation and to identify degradation mechanisms.

Our R&D Services on this Topic Include:

• Electrical simulation of components (Sentaurus TCAD)
• Optical simulation (transfer matrix and RCWA)
• Electro-optical characterization to identify functional principles and limiting components in the solar cells
• Imaging methods (thermography, spatially resolved photocurrent, electroluminescence, photoluminescence) to localize defects and optimize coatings and production processes.

All Research Projects on the Topic "Perovskite Thin-Film Photovoltaics"