Optical properties of lead-free Cs3Bi2I9 nanowire arrays prepared by template

Abstract

Bismuth-based (Bi) perovskites have garnered significant interest as alternatives to lead-based (Pb) perovskites in photoelectric applications due to their non-toxicity and diverse structural properties. However, the inherent high limitation of electrons presents a significant challenge to their further utilization in various applications. Herein, all-inorganic Cs3Bi2I9 nanowire arrays have been successfully prepared by AAO template combined with the two-step method of low-temperature solution. Compared to the Cs3Bi2I9 film, the Cs3Bi2I9 nanowire arrays obtained the higher photoluminescence intensity, indicating a strong interaction between Cs3Bi2I9 and AAO, resulting from the significant weakening of the high electron confinement in the valence band of Cs3Bi2I9, which presenting as the valence band of the Cs3Bi2I9-AAO is mainly contributed by the O 2p orbital, while the conduction band does not change significantly. In addition, the Cs3Bi2I9 nanowire arrays have been demonstrated with the enhanced environmental and thermal stability, which maintain 90 % of their initial photoluminescence intensity after 120 h (in a vacuum) heating at 80 °C or after 10 days in the air (relative humidity of 40 %).