Shuaifeng Hu, Henry J. Snaith of the University of Oxford, and Atsushi Wakamiya of Kyoto University published a research paper titled "Steering perovskite precursor solutions for multijunction photovoltaics" in the journal Nature. Shuaifeng Hu is the first author, and Shuaifeng Hu, Atsushi Wakamiya, and Henry J. Snaith are co-corresponding authors.
Key Highlights: This paper, through in-depth investigation of the chemical properties of tin-lead perovskite precursor solutions, successfully fabricated single-, double-, and triple-junction perovskite solar cells, achieving PCEs of 23.9%, 29.7%, and 28.7%, respectively (the highest certified efficiency is 29.26%). Furthermore, the encapsulated triple-junction cells exhibited excellent long-term stability under operating conditions, achieving an initial efficiency of 80%.
Perovskite solar cells have become a hot topic in the photovoltaic field due to their potential for high efficiency and low cost. However, despite the excellent optoelectronic properties of perovskite materials, the application of narrow-bandgap tin-lead perovskites in thin-film devices faces a number of challenges, primarily the facile oxidation of Sn(II) to Sn(IV) and the difficulty in controlling the crystallization process. These issues limit the performance and stability of perovskite solar cells, particularly in multi-junction tandem photovoltaic devices. Therefore, improving the quality, uniformity, and optoelectronic properties of perovskite films has become a key issue that needs to be addressed.
In light of this, the team of Shuaifeng Hu, Henry J. Snaith, and Atsushi Wakamiya from the University of Oxford and Kyoto University focused on understanding the chemical properties of tin-lead perovskite precursor solutions. Their research revealed that Sn(II) plays a dominant role in interactions with the precursor and additives, carboxylic acids have a unique effect on the colloidal properties of the solution and film crystallization, and ammonium salts play a significant role in enhancing the optoelectronic properties of the films. By combining these two functional groups, the amino acid salt material significantly improves the semiconducting quality and uniformity of the perovskite films, surpassing the effects of either functional group alone. Based on these studies, scientists successfully fabricated single-, double-, and triple-junction perovskite solar cells, achieving PCEs of 23.9%, 29.7%, and 28.7%, respectively (with the highest certified efficiency reaching 29.26%). Furthermore, the encapsulated triple-junction cells demonstrated excellent long-term stability under operating conditions, maintaining an initial efficiency of 80%. Furthermore, quadruple-junction devices were fabricated, achieving an efficiency of 27.9% and a maximum open-circuit voltage of 4.94 V.
This research provides new insights for further improving the efficiency of tin-lead perovskite solar cells.
Source：https://doi.org/10.1038/s41586-024-08546-y