Thermodynamically stabilized β-CsPbI₃–based perovskite solar cells with efficiencies >18

• Published in: Science (American Association for the Advancement of Science) Vol. 365; no. 6453; pp. 591 - 595
• Main Authors: Wang, Yong, Dar, M. Ibrahim, Ono, Luis K., Zhang, Taiyang, Kan, Miao, Li, Yawen, Zhang, Lijun, Wang, Xingtao, Yang, Yingguo, Gao, Xingyu, Qi, Yabing, Grätzel, Michael, Zhao, Yixin
• Format: Journal Article
• Language: English
• Published: Washington American Association for the Advancement of Science 09.08.2019; The American Association for the Advancement of Science
• Subjects: Beta phase; Carrier lifetime; Cations; Choline; Cracks; Current carriers; Energy conversion efficiency; Energy gap; Inductively coupled plasma mass spectrometry; Iodides; Ions; Mass spectrometry; Mass spectroscopy; Perovskites; Phase stability; Photovoltaic cells; Pinholes; Scientific imaging; Secondary ion mass spectrometry; Solar cells; Spectral sensitivity; Spectroscopy; X-ray scattering
• ISSN: 0036-8075; 1095-9203; 1095-9203
• DOI: 10.1126/science.aav8680

Although β-CsPbI₃ has a bandgap favorable for application in tandem solar cells, depositing and stabilizing β-CsPbI₃ experimentally has remained a challenge.We obtained highly crystalline β-CsPbI₃ films with an extended spectral response and enhanced phase stability. Synchrotron-based x-ray scattering revealed the presence of highly oriented β-CsPbI₃ grains, and sensitive elemental analyses—including inductively coupled plasma mass spectrometry and time-of-flight secondary ion mass spectrometry—confirmed their all-inorganic composition. We further mitigated the effects of cracks and pinholes in the perovskite layer by surface treating with choline iodide, which increased the charge-carrier lifetime and improved the energy-level alignment between the β-CsPbI₃ absorber layer and carrier-selective contacts. The perovskite solar cells made from the treated material have highly reproducible and stable efficiencies reaching 18.4% under 45 ± 5°C ambient conditions.