FA4Pb2I7.5(SCN)0.5: n = 3 Member of Perovskite Homologous Series FAn+1Pbn−1I3n−1.5(SCN)0.5 with Columnar Defects

Takuya Ohmi, James R. Neilson, Wataru Taniguchi, Tomoya Fukui, Teppei Nagase, Yuki Haruta, Makhsud I. Saidaminov, Takanori Fukushima, Masaki Azuma, Takafumi Yamamoto

Hybrid organic–inorganic halide perovskites are an emerging class of optoelectronic materials. Among them, there are many homologous series of Ruddlesden–Popper and Dion–Jacobson layered perovskites reported, but a homologous series based on defect ordering has not yet been discovered. Here, by using thiocyanate anion as a defect generator, we successfully synthesized a new defect-ordered perovskite FA₄Pb₂I_7.5(SCN)_0.5 together with the previously reported FA₆Pb₄I_13.5(SCN)_0.5. These compounds can be represented respectively as n = 3 and n = 5 members of the perovskite homologous series FA_n+1Pb_n−1I_3n−1.5(SCN)_0.5 with ordered columnar defects, which is the first homologous series of defect-ordered hybrid perovskites. The optical band gap increases with an increase in the ordered defects in the lattice. FA₄Pb₂I_7.5(SCN)_0.5 (n = 3) exhibits photoluminescence emission, which is a feature of layered perovskites with a quantum-well structure. This study provides a new strategy to control the defect orderings for tuning their optical properties by incorporating thiocyanate.

Press release


ACS Materials Letter, 6, 1913–1919, (2024). (DOI: 10.1021/acsmaterialslett.3c01514)
https://pubs.acs.org/doi/10.1021/acsmaterialslett.3c01514