Ecole polytechnique fédérale de Lausanne (EPFL) - Page 4

Researchers from the University of Toronto, the University of Kentucky, EPFL, North Carolina State University and Northwestern University have designed a perovskite solar cell that can stand up to high temperatures for more than 1,500 hours — an important achievement on the to commercialization. 

“Perovskite solar cells offer new pathways to overcome some of the efficiency limitations of silicon-based technology, which is the industrial standard today,” said Ted Sargent, professor of electrical and computer engineering at the McCormick School of Engineering, professor of chemistry in the Weinberg College of Arts and Sciences, and a former professor at the University of Toronto. “But due to its multi-decade head start, silicon still has an advantage in some areas, including stability. This study shows how we can close that gap.”

In two separate studies, researchers report novel methods that enable the fabrication of high-performance perovskite-silicon tandem solar cells with power conversion efficiencies exceeding 30%. 

Combining perovskite and silicon solar cells into a tandem device could provide a promising path toward high-performance PVs. Here, in the two separate studies, researchers present different strategies for developing perovskite-silicon tandem solar cells with a PCE exceeding 30%. In one study, Xin Yu Chin from Ecole Polytechnique Fédérale de Lausanne (EPFL) and colleagues showed that the uniform deposition of the perovskite top cell on a silicon bottom cell featuring micrometric pyramids – the industry standard configuration – can facilitate high photocurrents in tandem solar cells.

An international team of scientists from Fritz Haber Institute of the Max Planck Society, École Polytechnique in Paris, Columbia University in New York, and the Free University in Berlin have demonstrated laser-driven control of fundamental motions of the lead halide perovskite (LHP) atomic lattice.

Sketch of the experimental pump-probe configuration. Image from Science Advances

By applying a sudden electric field spike faster than a trillionth of a second (picosecond) in the form of a single light cycle of far-infrared Terahertz radiation, the team unveiled the ultrafast lattice response, which might contribute to a dynamic protection mechanism for electric charges. This precise control over the atomic twist motions could allow to create novel non-equilibrium material properties, potentially providing hints for designing the solar cell material of the future.

An international research team that includes scientists from EPFL in Switzerland, Middle East Technical University (METU) in Turkey, Lomonosov Moscow State University in Russia and The University of Tokyo has fabricated a quasi-2D perovskite solar cell with a unique type of salt to enhance hole extraction. 

The triple-cation perovskite absorber was treated with phenethylammonium iodide (PEAI), a modulator that alters the perovskite film's surface energy and forms a quasi-2D structure without further annealing. The result is a 23.08%-efficient device that is also able to retain 95% of its initial efficiency after 900 hours.

Researchers from the University of Toronto in Canada, Northwestern University, The University of Toledo and University of North Carolina at Chapel Hill in the United States, King Abdullah University of Science and Technology (KAUST) in Saudi Arabia, Yunnan University in China, Ecole Polytechnique Fedérale de Lausanne (EPFL) in Switzerland and University of Warwick in the UK have developed a triple-junction perovskite solar cell with a record efficiency of 24.3% with an open-circuity voltage of 3.21 V. 

The NREL has certified the cell’s quasi-steady-state efficiency as 23.3%, which the team stated is the first reported certified efficiency for perovskite-based triple-junction solar cells. They added that triple-junction perovskite solar cells have so far demonstrated a maximum efficiency of around 20%.