Hu Shuaifeng, Thiesbrummel Jarla, Pascual Jorge, Stolterfoht Martin, Wakamiya Atsushi, Snaith Henry J
Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, United Kingdom.
Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan.
Chem Rev. 2024 Apr 10;124(7):4079-4123. doi: 10.1021/acs.chemrev.3c00667. Epub 2024 Mar 25.
All-perovskite tandem solar cells are attracting considerable interest in photovoltaics research, owing to their potential to surpass the theoretical efficiency limit of single-junction cells, in a cost-effective sustainable manner. Thanks to the bandgap-bowing effect, mixed tin-lead (Sn-Pb) perovskites possess a close to ideal narrow bandgap for constructing tandem cells, matched with wide-bandgap neat lead-based counterparts. The performance of all-perovskite tandems, however, has yet to reach its efficiency potential. One of the main obstacles that need to be overcome is the─oftentimes─low quality of the mixed Sn-Pb perovskite films, largely caused by the facile oxidation of Sn(II) to Sn(IV), as well as the difficult-to-control film crystallization dynamics. Additional detrimental imperfections are introduced in the perovskite thin film, particularly at its vulnerable surfaces, including the top and bottom interfaces as well as the grain boundaries. Due to these issues, the resultant device performance is distinctly far lower than their theoretically achievable maximum efficiency. Robust modifications and improvements to the surfaces of mixed Sn-Pb perovskite films are therefore critical for the advancement of the field. This Review describes the origins of imperfections in thin films and covers efforts made so far toward reaching a better understanding of mixed Sn-Pb perovskites, in particular with respect to surface modifications that improved the efficiency and stability of the narrow bandgap solar cells. In addition, we also outline the important issues of integrating the narrow bandgap subcells for achieving reliable and efficient all-perovskite double- and multi-junction tandems. Future work should focus on the characterization and visualization of the specific surface defects, as well as tracking their evolution under different external stimuli, guiding in turn the processing for efficient and stable single-junction and tandem solar cell devices.
全钙钛矿串联太阳能电池在光伏研究中引起了广泛关注，因为它们有可能以经济高效且可持续的方式超越单结电池的理论效率极限。由于带隙弯曲效应，混合锡铅（Sn-Pb）钙钛矿具有接近理想的窄带隙，适合用于构建串联电池，与宽带隙的纯铅基对应物相匹配。然而，全钙钛矿串联电池的性能尚未达到其效率潜力。需要克服的主要障碍之一是混合Sn-Pb钙钛矿薄膜的质量常常较低，这在很大程度上是由于Sn(II)容易氧化为Sn(IV)，以及难以控制的薄膜结晶动力学所致。钙钛矿薄膜中还引入了其他有害缺陷，特别是在其易受损的表面，包括顶部和底部界面以及晶界。由于这些问题，所得器件的性能明显远低于其理论上可实现的最大效率。因此，对混合Sn-Pb钙钛矿薄膜表面进行有力的改性和改进对于该领域的发展至关重要。本综述描述了薄膜中缺陷的起源，并涵盖了迄今为止为更好地理解混合Sn-Pb钙钛矿所做的努力，特别是关于改善窄带隙太阳能电池效率和稳定性的表面改性方面。此外，我们还概述了集成窄带隙子电池以实现可靠且高效的全钙钛矿双结和多结串联电池的重要问题。未来的工作应专注于特定表面缺陷的表征和可视化，以及跟踪它们在不同外部刺激下的演变，进而指导高效稳定的单结和串联太阳能电池器件的加工。
