Researchers at the Fraunhofer Institute for Integrated Systems and Device Technology (Fraunhofer IISB) have claimed that they have identified how impurities are formed in silicon crystals during their manufacturing process.

Through various targeted experiments, the researchers discovered that the crucible and coating systems are the biggest sources of metallic impurities in silicon crystals. They added that the outcome of their experiments could help improve the quality of crystalline silicon.

Crystalline silicon is the dominant semiconducting material used for the production of solar cells. According to the researchers, the high concentration of metals like iron, cobalt, and chromium in the silicon crystal plays a significant role in reducing the performance and quality of solar cells.

The researchers developed a numerical simulation model to calculate the distribution of unknown metals in the silicon crystal. The model took into account the silicon nitride coating, the degree of contamination of the crucible, silicon raw materials, and the relevant parameters to control the process. The outcome of the process revealed that the increased purity of all auxiliary materials would reduce the metal containment in the silicon crystal to enhance its quality.

The r. Researchers added that it would help manufacturers enhance the quality of the crystalline silicon and reduce the production cost.

Researchers at the Fraunhofer Institute for Solar Energy Systems ISE also announced a new record efficiency of 25.9% for the III-V/Si tandem solar cell grown directly on silicon.

The joint project SYNERGIE – “Synergetic further development of supplier products to reduce manufacturing costs and increase the material quality of crystalline silicon blocks in photovoltaics” – was funded by the Federal Ministry for Economic Affairs and Energy (BMWi). Project partners of Fraunhofer IISB were AlzChem Group and Wacker Chemie.

Mercom earlier reported that researchers at the National Renewable Energy Laboratory (NREL) had conducted the first global assessment of various approaches used to manage solar photovoltaic (PV) modules at the end of their life spans. The study was published in the scientific journal Nature Energy.

The study focused on the recycling of crystalline silicon, which is used in 90% of installed solar PV modules in a very pure form. The silicon accounts for nearly half of the energy produced and half of the cost to produce solar PV modules, but it accounts for only a small portion of the mass. Its purity determines the value of crystalline silicon.

Image credit: Stephan Kambor / CC BY-SA