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Structure and optical properties of layered perovskite (MA)2BbI2–xBrx(SCN)2 (0 ≤ x < 1.6)

DOI: 10.1021/acs.inorgchem.0c02686 DOI Help

Authors: Takafumi Yamamoto (Kyoto University) , Iain W. H. Oswald (Colorado State University) , Christopher N. Savory (University College London) , Takuya Ohmi (Tokyo Institute of Technology) , Alexandra A. Koegel (Colorado State University) , David O. Scanlon (University College London; Diamond Light Source) , Hiroshi Kageyama (Kyoto University) , James R. Neilson (Colorado State University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Inorganic Chemistry

State: Published (Approved)
Published: November 2020

Abstract: The layered perovskite (MA)2PbI2(SCN)2 (MA = CH3NH3+) is a member of an emerging series of compounds derived from hybrid organic–inorganic perovskites. Here, we successfully synthesized (MA)2PbI2–xBrx(SCN)2 (0 ≤ x < 1.6) by using a solid-state reaction. Despite smaller bromide substitution for iodine, 1% linear expansion along the a axis was observed at x ∼ 0.4 due to a change of the orientation of the SCN– anions. Diffuse reflectance spectra reveal that the optical band gap increases by the bromide substitution, which is supported by the DFT calculations. Curiously, bromine-rich compounds where x ≥ 0.8 are light sensitive, leading to partial decomposition after ∼24 h. This study demonstrates that the layered perovskite (MA)2PbI2(SCN)2 tolerates a wide range of bromide substitution toward tuning the band gap energy.

Subject Areas: Chemistry, Materials

Facility: BL02B2 at SPring-8