A Narrow Bandgap of 2D Ruddlesden-Popper Bilayer Perovskite with Giant Entropy Change and Photoluminescence

The multifunctional two-dimensional (2D) organic-inorganic hybrid perovskites have potential applications in many fields, such as, semiconductor, energy storage and fluorescent device etc. Here, a 2D Ruddlesden-Popper (RP) perovskite (IPA)(2)(FA)Pb2I7 (1, IPA(+)=C3H9NI+, FA(+)=CN2H5+) is determined for its photophysical properties. Strikingly, 1 reveals a solid reversible phase transition with T-c of 382 K accompanied by giant entropy change of 40 J mol(-1) K-1. Further optical investigations indicate that 1 reveals a narrow direct bandgap (2.024 eV) attributed to the slight bending of I-Pb-I edge and inorganic [Pb2I7](n) layer and a superior photoluminescence (PL) emission with super long lifetime of 0.1607 ms. It is believed that this work will pave an avenue to further design multifunctional semiconductors that combines energy storage and photoelectric materials.

Automated summary

The research identifies the photophysical properties of a two-dimensional organic-inorganic hybrid perovskite, showing solid phase transition with significant entropy change, narrow bandgap, and excellent luminescence properties, paving the way for the design of multifunctional semiconductors.