An international collaboration led by Antonio Abate, HZB, and Zhao-Kui Wang, Institute of Functional Nano & Soft Materials (FUNSOM), Soochow University, China, has achieved a breakthrough that opens up a path to non-toxic perovskite-based solar cells that provides stable performance over a long period.
They use tin instead of lead but have created a two-dimensional structure by inserting organic groups within the material, which leads to so-called 2D Ruddlesden-Popper phases.
University of Groningen scientists are investigating in situ how lead-free perovskite crystals form and how the crystal structure affects the functioning of the solar cells, as part of their quest to find alternatives to lead-based perovskites.
The best results in solar cells have been obtained using perovskites with lead as the central cation. As this metal is toxic, tin-based alternatives have been developed, for example, formamidinium tin iodide (FASnI3). This is a promising material; however, it lacks the stability of some of the lead-based materials. Attempts have been made to mix the 3D FASnI3 crystals with layered materials, containing the organic cation phenylethylammonium (PEA). "My colleague, Professor Maria Loi, and her research team showed that adding a small amount of this PEA produces a more stable and efficient material," says Assistant Professor Giuseppe Portale. "However, adding a lot of it reduces the photovoltaic efficiency".
Researchers at the Pohang University of Science & Technology (POSTECH) have developed eco-friendly-solvent processable hole transport polymers by using peppermint oil and walnut aroma food additives and the polymer can prevent lead leakage.
The POSTECH research team consisted of Prof. Taiho Park and Junwoo Lee, that developed Alkoxy-PTEG - hole transport polymers that could be dissolved in peppermint oil, by applying ethylene glycol side chains when producing perovskite solar cells. Also, the team confirmed that this polymer captured leaking lead in aging perovskite solar cells.
Researchers at Northern Illinois University and the U.S. Department of Energy’s (DOE) National Renewable Energy Laboratory (NREL) in Colorado have reported on a potential breakthrough in the development of hybrid perovskite solar cells.
Led by Tao Xu of NIU and Kai Zhu of NREL, the scientists have developed a technique to sequester the lead used to make perovskite solar cells and minimize potential toxic leakage by applying lead-absorbing films to the front and back of the solar cell.
Researchers led by Prof. Antonio Abate at the Helmholtz-Zentrum Berlin have designed a study to investigate lead hazards relating to perovskite soar cells. They cooperated with plant scientists from the Fujian Agriculture and Forestry University, China, where the experiments were carried out, and with a group from the university of Naples, Italy.
Mint plants grown on control soil (left) and perovskite-contaminated soil (right). Credit: Nature
The plant experts prepared contaminated soil samples with different concentrations of lead from either perovskite solar cells or other lead sources and cultivated different plants. After a growth period, they analyzed the lead content in leaves and other parts of the plant. They found that lead from perovskite solar cells is 10 times more bioavailable than lead from other industrial sources.