CNR ExploRA

Articolo in rivista, 2022, ENG, 10.1021/acs.jpclett.2c02313

Solid-State Nuclear Magnetic Resonance of Triple-Cation Mixed-Halide Perovskites

Noemi Landi, Elena Maurina, Daniela Marongiu, Angelica Simbula, Silvia Borsacchi, Lucia Calucci, Michele Saba, Elisa Carignani, and Marco Geppi

a Department of Chemistry and Industrial Chemistry, University of Pisa, via G. Moruzzi 13, Pisa, 56124, Italy b Department of Physics, University of Cagliari, S.P. Monserrato-Sestu Km. 0700, Cagliari, Monserrato, 09042, Italy c Institute for the Chemistry of OrganoMetallic Compounds - ICCOM, Italian National Research Council - CNR, via G. Moruzzi 1, Pisa, 56124, Italy d Center for Instrument Sharing, University of Pisa (CISUP), Pisa, 56126, Italy

Mixed-cation lead mixed-halide perovskites are the best candidates for perovskite-based photovoltaics, thanks to their higher efficiency and stability compared to the single-cation single-halide parent compounds. TripleMix (Cs0.05MA0.14FA0.81PbI2.55Br0.45 with FA = formamidinium and MA = methylammonium) is one of the most efficient and stable mixed perovskites for single-junction solar cells. The microscopic reasons why triple-cation perovskites perform so well are still under debate. In this work, we investigated the structure and dynamics of TripleMix by exploiting multinuclear solid-state nuclear magnetic resonance (SSNMR), which can provide this information at a level of detail not accessible by other techniques. 133Cs, 13C, 1H, and 207Pb SSNMR spectra confirmed the inclusion of all ions in the perovskite, without phase segregation. Complementary measurements showed a peculiar longitudinal relaxation behavior for the 1H and 207Pb nuclei in TripleMix with respect to single-cation single-halide perovskites, suggesting slower dynamics of both organic cations and halide anions, possibly related to the high photovoltaic performances.

The journal of physical chemistry letters 13 (40), pp. 9517–9525