Efficient, stable silicon tandem cells enabled by anion-engineered wide-bandgap perovskites

• Published in: Science (American Association for the Advancement of Science) Vol. 368; no. 6487; pp. 155 - 160
• Main Authors: Kim, Daehan, Jung, Hee Joon, Park, Ik Jae, Larson, Bryon W., Dunfield, Sean P., Xiao, Chuanxiao, Kim, Jekyung, Tong, Jinhui, Boonmongkolras, Passarut, Ji, Su Geun, Zhang, Fei, Pae, Seong Ryul, Kim, Minkyu, Kang, Seok Beom, Dravid, Vinayak, Berry, Joseph J., Kim, Jin Young, Zhu, Kai, Kim, Dong Hoe, Shin, Byungha
• Format: Journal Article
• Language: English
• Published: United States The American Association for the Advancement of Science 10.04.2020; American Association for the Advancement of Science (AAAS)
• Subjects: Anions; Bromine; Efficiency; Electrical properties; Illumination; Iodides; Iodine; Photovoltaic cells; Silicon; Solar cells
• ISSN: 0036-8075; 1095-9203; 1095-9203
• DOI: 10.1126/science.aba3433

The bandgap of the perovskite top layer in tandem silicon solar cells must be tuned to ∼1.7 electron volts. Usually, the cation composition is varied because the bromine-rich anion compositions with wide bandgaps are structurally unstable. Kim et al. show that by using phenethylammonium as a two-dimensional additive, along with iodine and thiocyanate, bromine-rich perovskite films can be stabilized. A tandem silicon cell delivered >26% certified power conversion efficiency, and a perovskite device maintained 80% of its initial power conversion efficiency of >20% after 1000 hours under illumination. Science , this issue p. 155 Thiocyanate as a two-dimensional additive enhanced perovskite carrier mobility and stability in silicon tandem solar cells. Maximizing the power conversion efficiency (PCE) of perovskite/silicon tandem solar cells that can exceed the Shockley-Queisser single-cell limit requires a high-performing, stable perovskite top cell with a wide bandgap. We developed a stable perovskite solar cell with a bandgap of ~1.7 electron volts that retained more than 80% of its initial PCE of 20.7% after 1000 hours of continuous illumination. Anion engineering of phenethylammonium-based two-dimensional (2D) additives was critical for controlling the structural and electrical properties of the 2D passivation layers based on a lead iodide framework. The high PCE of 26.7% of a monolithic two-terminal wide-bandgap perovskite/silicon tandem solar cell was made possible by the ideal combination of spectral responses of the top and bottom cells.