[(CH₃)₃NH]₃Bi₂I₉: A Polar Lead‐Free Hybrid Perovskite‐Like Material as a Potential Semiconducting Absorber

Abstract

Abstract Perovskite hybrids of lead organometal halides, most notably CH 3 NH 3 PbI 3 , have shown extremely promising applications in the field of optoelectronics, because of their remarkable semiconducting and light‐absorbing properties. However, two key issues—the toxicity of lead and the poor ambient instabilities—have restrained their further commercialization. Herein, we have designed a new stable polar lead‐free hybrid material by utilizing the strategy of cation substitution, [(CH 3 ) 3 N] 3 Bi 2 I 9 ( 1 ), which adopts the 0D inorganic perovskite‐like architecture by face‐sharing BiI 6 octahedra. It is interesting that 1 displays excellent absorbing properties with a narrow optical band gap of ≈2.0 eV, and positive temperature‐dependent conductivity confirms its semiconducting behaviors. In addition, 1 has good phase stability against decomposition under ambient conditions, much superior to that of CH 3 NH 3 PbI 3 . This work suggests the potential of 1 as a lead‐free semiconducting absorber with high phase stability for photoelectric applications.