Perovskite Solar Cells: paving the way for rational ink design for industrial-scale manufacturing

Schematic illustration: the solvants (ink) are used to produce a thin film of polycrystalline perovskite. 

Schematic illustration: the solvants (ink) are used to produce a thin film of polycrystalline perovskite.  © HZB

For the production of high-quality metal-halide perovskite thin-films for large area photovoltaic modules often optimized inks are used which contain a mixture of solvents. An HZB team at BESSY II has now analysed the crystallisation processes within such mixtures. A model has also been developed to assess the kinetics of the crystallisation processes for different solvent mixtures. The results are of high importance for the further development of perovskite inks for industrial-scale deposition processes of these semiconductors.

Hybrid organic perovskite semiconductors are a class of materials for solar cells, which promise high efficiencies at low costs. They can be processed from precursor solutions that upon evaporation on a substrate form a polycrystalline thin film. Simple manufacturing processes, such as spin coating a precursor solution, often only lead to good results on a laboratory scale, i.e. for very small samples.

Printing large areas

For the production of larger area photovoltaic modules, the team of Dr. Eva Unger develops printing and coating processes in which the perovskite semiconductor is processed from inks containing the precursors dissolved in solvents.  The composition of the ink determines the material formation mechanism with the solvent affecting the process by its rheological properties, evaporation rate and participation in intermediate phases. "Our research question in this project was: How can we rationalize the difference in crystallization kinetics when using different solvents," explains Unger, who heads the Young Investigator Group Hybrid Materials Formation and Scaling.

Different evaporation rates

In solvents with only one component, the crystallization process is determined by the evaporation rate. "In mixtures of solvents, evaporation is dominated by the most volatile component that evaporates the fastest. This changes the ratio of solvents that are present upon crystallization", says Dr. Oleksandra Shargaieva, postdoc in Unger's team. 

Crystallization analyzed at BESSY II

At the KMC-2 beamline of BESSY II, she was able to analyse the formation of the perovskite semiconductor and crystalline intermediate phases incorporating solvent molecules during the evaporation of the solvents. “I found that the formation mechanism critically depends both on the solvents evaporation rate and binding strength to the lead-halide. “These insights will help to predict the kinetics of crystallization processes of the perovskite thin film for different solvent combinations based on the properties of the precursor solutions”, says Shargaieva.

"There is still a lack of systematic knowledge when scaling up from laboratory scale to industrial area sizes. With these results we pave the way for further ink design to enable industrial-scale manufacturing or perovskite thin films of high quality”, says Unger.

arö

  • Copy link

You might also be interested in

  • Metallic nanocatalysts: what really happens during catalysis
    Science Highlight
    10.09.2025
    Metallic nanocatalysts: what really happens during catalysis
    Using a combination of spectromicroscopy at BESSY II and microscopic analyses at DESY's NanoLab, a team has gained new insights into the chemical behaviour of nanocatalysts during catalysis. The nanoparticles consisted of a platinum core with a rhodium shell. This configuration allows a better understanding of structural changes in, for example, rhodium-platinum catalysts for emission control. The results show that under typical catalytic conditions, some of the rhodium in the shell can diffuse into the interior of the nanoparticles. However, most of it remains on the surface and oxidises. This process is strongly dependent on the surface orientation of the nanoparticle facets.
  • Shedding light on insulators: how light pulses unfreeze electrons
    Science Highlight
    08.09.2025
    Shedding light on insulators: how light pulses unfreeze electrons
    Metal oxides are abundant in nature and central to technologies such as photocatalysis and photovoltaics. Yet, many suffer from poor electrical conduction, caused by strong repulsion between electrons in neighboring metal atoms. Researchers at HZB and partner institutions have shown that light pulses can temporarily weaken these repulsive forces, lowering the energy required for electrons mobility, inducing a metal-like behavior. This discovery offers a new way to manipulate material properties with light, with high potential to more efficient light-based devices.
  • Key technology for a future without fossil fuels
    Interview
    21.08.2025
    Key technology for a future without fossil fuels
    In June and July 2025, catalyst researcher Nico Fischer spent some time at HZB. It was his sabbatical, he was relieved of his duties as Director of the Catalysis Institute in Cape Town for several months and was able to focus on research only. His institute is collaborating with HZB on two projects that aim to develop environmentally friendly alternatives using innovative catalyst technologies. The questions were asked by Antonia Rötger, HZB.