Effect of Co-Solvents on the Crystallization and Phase Distribution of Mixed-Dimensional Perovskites

Alessandro Caiazzo, Kunal Datta, Junke Jiang, María C. Gélvez-Rueda, Junyu Li, Riccardo Ollearo, J.M. Vicent-Luna, Shuxia Tao, Ferdinand C. Grozema, Martijn M. Wienk, René A.J. Janssen (Corresponding author)

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Solution-processed quasi-2D perovskites are promising for stable and efficient solar cells because of their superior environmental stability compared to 3D perovskites and tunable optoelectronic properties. Changing the number of inorganic layers (n) sandwiched between the organic spacers allows for tuning of the bandgap. However, narrowing the phase distribution around a specific n-value is a challenge. In-situ UV–vis–NIR absorption spectroscopy is used to time-resolve the crystallization dynamics of quasi-2D butylammonium-based (BA) perovskites with <n> = 4, processed from N,N-dimethylformamide (DMF) in the presence of different co-solvents. By combining with photoluminescence, transient absorption, and grazing-incidence wide-angle X-ray scattering, the crystallization is correlated to the distribution of phases with different n-values. Infrared spectroscopy and density functional theory reveal that the phase distribution correlates with perovskite precursor—co-solvent interaction energies and that stronger interactions shift the phase distribution towards smaller n-values. Careful tuning of the solvent/co-solvent ratio provides a more homogeneous phase distribution, with highly oriented perovskite crystals and suppressed formation of n = 1–2 phases, providing a power conversion efficiency for BA2MA3Pb4I13 solar cells that increases from 3.5% when processed from DMF to over 11% and 10% when processed from DMF/dimethyl sulfoxide and DMF/N-methyl-2-pyrrolidone mixtures, respectively.
Original languageEnglish
Article number2102144
Number of pages12
JournalAdvanced Energy Materials
Issue number42
Early online date5 Oct 2021
Publication statusPublished - 11 Nov 2021


FundersFunder number
European Union 's Horizon 2020 - Research and Innovation Framework Programme15CST04‐2
Horizon 2020 Framework Programme648433
Technische Universiteit Delft
Ministerie van Onderwijs, Cultuur en Wetenschap024.001.035
Nederlandse Organisatie voor Wetenschappelijk Onderzoek680.91.011


    • Ruddlesden-Popper perovskites
    • crystallization
    • film formation
    • solar cells
    • solvent engineering


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