Concurrent cationic and anionic perovskite defect passivation enables 27.4% perovskite/silicon tandems with suppression of halide segregation

by Furkan H. Isikgor, Francesco Furlan, Jiang Liu, Esma Ugur, Mathan K. Eswaran, Anand S. Subbiah, Emre Yengel, Michele De Bastiani, George T. Harrison, Shynggys Zhumagali, Calvyn T. Howells, Erkan Aydin, Mingcong Wang, Nicola Gasparini, Thomas G. Allen, Atteq ur Rehman, Emmanuel Van Kerschaver, Derya Baran, Iain McCulloch, Thomas D. Anthopoulos, Udo Schwingenschlögl, Frédéric Laquai, Stefaan De Wolf
Article Year: 2021 DOI:


Isikgor, F.H., Furlan, F., Liu, J., Ugur, E., Eswaran, M.K., Subbiah, A.S., Yengel, E., De Bastiani, M., Harrison, G.T., Zhumagali, S., Howells, C.T., Aydin, E., Wang, M., Gasparini, N., Allen, T.G., Ur Rehman, A., Van Kerschaver, E., Baran, D., McCulloch, I., Anthopoulos, T.D., Schwingenschlögl, U., Laquai, F., De Wolf, S. 

Extra Information

This study, which was recently published in Joule, reports a concurrent cationic and anionic perovskite defect passivation strategy using the phenformin hydrochloride molecule boosting the performance of monolithic perovskite/silicon tandem solar cells.


Stable and efficient perovskite/silicon tandem solar cells require defect passivation and suppression of light-induced phase segregation of the wide-band-gap perovskite. Here, we report how molecules containing both electron-rich and electron-poor moieties, such as phenformin hydrochloride (PhenHCl), can satisfy both requirements, independent of the perovskite’s surface chemical composition and its grain boundaries and interfaces. PhenHCl-passivated wide-band-gap (∼1.68 eV) perovskite p-i-n single-junction solar cells deliver an open-circuit voltage (VOC) ∼100 mV higher than control devices, resulting in power conversion efficiencies (PCEs) up to 20.5%. These devices do not show any VOC losses after more than 3,000 h of thermal stress at 85°C in a nitrogen ambient. Moreover, PhenHCl passivation improves the PCE of textured perovskite/silicon tandem solar cells from 25.4% to 27.4%. Our findings provide critical insights for improved passivation of metal halide perovskite surfaces and the fabrication of highly efficient and stable perovskite-based single-junction and tandem solar cells.


Perovskite Solar cells Tandems passivation silicon Photovoltaics phase segregation Wide band-gap Defects