An international research team has built an all-perovskite tandem solar cell based on a perovskite cell with a wide band gap and an efficiency of 20.5%. The 1 cm2 scale tandem device achieved the highest efficiency ever reported for all-perovskite solar cells of this size to date.
An international team of researchers led by China’s Nanjing University has fabricated a 1.05 cm2 all-perovskite tandem solar cell with an efficiency of 28.2%.
“We focused on the performance loss caused by all-perovskite tandem solar cells during the scaling process from 0.05 cm2 to 1 cm2. Therefore, our challenge is how to fabricate perovskite tandem devices with large area and high efficiency. We believe that we should first focus on the interface issues in wide bandgap perovskite solar cells,” said Yurui Wang, the first author of the study. pv magazine.
The team noted that the certified efficiency is a record for all-perovskite tandem cells of this size. The research appears in “Homogenized contact in all-perovskite tandems using tailor-made 2D perovskite,” published in nature.
The team addressed the interface losses in the buckminster fullerene (C60) electron transport layer (ETL) of the wide bandgap top perovskite cell. “We found that the deposition of C60 can cause a deterioration in device uniformity, even though we have discovered similar patterns in previously published papers, but these phenomena have not received sufficient attention,” Wang explained.
The interface homogenization strategy involved applying a mixture of 4-fluorophenethylamine (F-PEA) and 4-trifluoromethyl-phenylammonium (CF3-PA) to create a two-dimensional (2D) layer that reduced contact losses and increased homogeneity, where the CF3-PA that improves charge extraction and transport.
The result was a top cell with an open-circuit voltage of 1.35 V, an efficiency of 20.5% and an energy bandgap of 1.77 eV on the cm2 scale. The team stacked the cell with a narrow bandgap perovskite subcell to create a 1.05 cm2 all-perovskite tandem cell with a certified efficiency of 28.2%. Both results have been certified by Japan Electrical Safety and Environment Technology Laboratories (JET).
The group concluded that the work “demonstrates the importance of treating the top perovskite/ETL contact for scaling up perovskite solar cells.”
The technology is expected to be further developed by Renshine Solar, a startup company founded by co-corresponding author Hairen Tan, Wang said.
“We will continue to pay attention to the scientific issues within photovoltaic devices, develop the scalable preparation process for all-perovskite tandem solar cells, and make continuous efforts to promote the commercialization of this technology,” Wang said, referring to the future direction of the group’s work . “Our ultimate goal will be to achieve higher efficiency, larger surface area, greater stability and lower costs on tandem devices.”
The research group was formed by academics from Nanjing University, Renshine Solar, Jilin University and the Chinese Academy of Sciences, as well as scientists from the University of Cambridge in Britain, the University of Victoria in Canada and the Australian National University.
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