Synchronizing crystallization enables thermally stable all-FA Pb–Sn perovskites for printable MA-free all-perovskite tandem solar cells

Li H, Feng W, Wei J, He Q, Shen H, He Y, Chen S, Hao Y, Brabec C, Mai Y, Guo F (2026)

Publication Type: Journal article

Publication year: 2026

Journal

Energy and Environmental Science Royal Society of Chemistry

DOI: 10.1039/d5ee04529k

Abstract

Monolithic all-perovskite tandem solar cells based on mixed cation lead–tin (Pb–Sn) have advanced rapidly in recent years. However, the presence of a considerable amount of volatile methylammonium (MA) adversely constrains the stability of solar devices. Here, we first quantitatively evaluated the thermal stability of Pb–Sn perovskite films containing different types of A-site cations. In comparison to the all-MA and MA–FA binary counterparts, all-formamidinium (FA) Pb–Sn films exhibit the highest decomposition activation energy of 149.13 kJ mol−1. On this basis, high-quality all-FA Pb–Sn perovskite films are prepared by blade coating with addition of a small amount of hydrazinium dichloride (HDC) to the perovskite precursor. The selectively strong coordination of HDC with Sn2+ ions not only suppresses the oxidation of Sn2+ but, more importantly, balances the nucleation of the Sn- and Pb-based species, resulting in perovskite films with markedly improved homogeneity of the Pb–Sn alloyed phase. The prepared single-junction all-FA Pb–Sn PSCs and MA-free tandem devices yield champion efficiencies of 21.81% and 27.40%, respectively. Moreover, the unencapsulated all-FA Pb–Sn devices retain >80% of their initial efficiencies following 190 h of thermal stress at 85 °C.

Authors with CRIS profile

Christoph Brabec Institute Materials for Electronics and Energy Technology (i-MEET)

Involved external institutions

Jinan University (JNU) / 暨南大学 CN China (CN) Henan University / 河南大学 CN China (CN) Taiyuan University of Technology CN China (CN)

How to cite

APA:

Li, H., Feng, W., Wei, J., He, Q., Shen, H., He, Y.,... Guo, F. (2026). Synchronizing crystallization enables thermally stable all-FA Pb–Sn perovskites for printable MA-free all-perovskite tandem solar cells. Energy and Environmental Science. https://doi.org/10.1039/d5ee04529k

MLA:

Li, Hongbing, et al. "Synchronizing crystallization enables thermally stable all-FA Pb–Sn perovskites for printable MA-free all-perovskite tandem solar cells." Energy and Environmental Science (2026).

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