CC BY
17LD-I-8
Monodisperse formamidinium tin iodide nanocrystals
D. N. Dirin12, A. Vivani13, M. I. Bodnarchuk2, M. Aebli1, I. Cherniukh12, A. Guagliardi34, M. V.
Kovalenko1'2*
1Department of Chemistry and Applied Biosciences, ETH Zürich 2Laboratory for Thin Films and Photovoltaics, Empa 3University of Insubria, Department of Science and High Technolog
4Institute of Crystallography, Italy
Over the last nine years, lead halide perovskites have been a subject of continuous interest due to a combination of several unique properties, particularly long diffusion length of carriers, optoelectronic tolerance to intrinsic defects, and highly dynamic crystal lattice. These materials have exhibited the well-recognized success towards application in solar cells, light-emitting devices, and high-energy radiation detectors. There was also significant progress in the understanding of the origin of their unique optoelectronic properties on both bulk- and nano-scale levels. This new understanding indicates that finding an alternative lead-free material with similar optoelectronic properties among other, non-group-14 metal halides can be very challenging if possible at all. On the other hand, recent advances in metal halide perovskite photovoltaics indicate that the closest analog to lead halide perovskites, namely formamidinium tin iodide, could exhibit similarly exciting performance if synthesized with a low number of trap states. The main challenge with this material relates to the easiness of trap states generation during the processing of this material, which is often ascribed to the oxidation of Sn(II) to Sn(IV). In this work we present a new synthesis of colloidal formamidinium tin iodide nanocrystals with a high degree of monodispersity and show that such oxidation is not the only pathway of formamidinium tin iodide degradation and low photoluminescence quantum yield.
