[(4AMTP)PbBr 2 ] 2 PbBr 4 : a Nontypical Cation-Coordinated Perovskite Showing Deep-Blue Emissions and Blue-Light Photoelectric Response.

Metal-halide perovskites have been extensively investigated due to their fascinating structural diversity and outstanding optoelectronic properties. We report the photoluminescence and photoelectric response behavior of a nontypical Dion-Jacobson perovskite [(4AMTP)PbBr 2 ] 2 PbBr 4 (4AMTP = 4-aminomethyltetrahydropyran cation), featuring neutral PbBr 2 layers incorporated into the cationic layers between the anionic [PbBr 4 ] 2- layers. A 4AMTP-coordinated PbBr 2 unit constitutes the unique nontypical dication layer. The seven-coordinated PbBr 6 O unit forms a largely distorted decahedron with a short distance from the inorganic [PbBr 4 ] 2- layer. The photoluminescence behavior of [(4AMTP)PbBr 2 ] 2 PbBr 4 shows crystal size dependence. Larger crystals show purplish-blue emission with two peaks at 414 and 431 nm, whereas smaller grain size (<50 μm) crystals demonstrate a single emission peak at 425 nm. Meanwhile, it shows a blue-light photoelectric response under the illumination of 405 nm with an on/off ratio of 175 for single-crystal devices and 97 for thin-film devices. The photoresponse performance is proportional to the molar extinction coefficient of the absorption band edge.