Monofluorine substitution achieved high-Tc dielectric transition in a one-dimensional lead bromide hybrid photoluminescent perovskite semiconductor

Abstract

High-T_c phase transition materials are essential for practical applications in energy and data storage, etc. Compared with the traditional deuterium isotope effect and newly discovered stress engineering, monofluorine substitution as a simple and universal method demonstrates many advantages over the above to enhance the T_c. In this report, we synthesized a one-dimensional hybrid lead bromide perovskite of (FTEA)PbBr₃ (FTEA = Et₃NCH₂CH₂F) by the monofluorine substitution of (Et₄N)PbBr₃. After fluoridation, (FTEA)PbBr₃ retains the crystal symmetry unchanged and shows similar phase transition behavior with an Aizu notation of 6/mmmF2/m. The origin of the phase transition continues to be the order–disorder transition of a monofluorine substituted organic cation. However, the T_c experiences a significant enhancement of 16 K. Therefore, fluorine substitution provides a broad application range to improve the T_c. Moreover, (FTEA)PbBr₃ undergoes excellent switchable dielectric transition coupled with semiconducting properties with an indirect bandgap of 3.48 eV. Unexpectedly, the title compound demonstrates a bright red emission under a UV lamp. Monofluorine substitution achieved significant T_c enhancement and the observation of multiple coupling of the switchable dielectric, semiconducting, and photoluminescent properties in a one-dimensional lead bromide halide perovskite will promote the further development of phase transition materials.