Thermal-Induced Ferroelastics in Two Lead-Free Organic-Inorganic Hybrid Perovskites

Lead-based organic-inorganic hybrids occupy a niche in the field of optoelectronics due to exceptional semiconducting properties and potential ferroelasticity.Nevertheless,the possible toxicity of lead restricts their widespread application to a certain extent.Herein,two new lead-free ferroelastic semiconductors are reported:[DMMClEA]_(3)Bi_(2)Br_(9)(compound 1)and[DMMClEA]_(3)Sb_(2)Br_(9)(compound 2)(DMMClEA=N-(chloromethyl)-N,N-dimethylethylammonium),in which the inorganic framework neatly arranges with[Bi_(2)Br_(9)]^(3−)/[Sb_(2)Br_(9)]^(3−)polyhedrons shared by face,forming an A_(3)B_(2)X_(9)-type structure.Both compounds 1 and 2 possess two-step phase transitions,including a3mF2/m-type ferroelastic phase transition,based on the Aizu rule.In addition,dual dielectric switches endow the application toward sensor devices.This finding enriches A_(3)B_(2)X_(9)-type zero-dimensional hybrid ferroelastics and provides an approach to designing high-performance,lead-free perovskite semiconductors with dielectric functionality.

Hybrid perovskite shows temperature-dependent photoluminescence and dielectric response triggered by halogen substitution

Materials exhibiting dielectric switching response and photoluminescence(PL)are promising for sensors and information storage.In previous research,we synthesized a series of materials with red or green PL and dielectric switching capabilities by incorporating luminescent metal halides into organic ammonium compounds.However,effective modification to synthesize organic-inorganic hybrid materials with dielectric switching response and orange PL continues to be a challenge in the respective fields.Orange PL materials are valuable for switching and sensors,and most orange light sources are derived from rare earth elements,making them harder to obtain.We have successfully synthesized two organic-inorganic hybrid materials([CMPD]PbBr_(3)(1)and[BMPD]PbBr_(3)(2),CMPD=N-ClCH_(2)-N-methylpiperidine,BMPD=N-BrCH_(2)-N-methylpiperidine)that exhibit both orange PL and dielectric switching response.When Cl in compound 1 is substituted by Br in compound 2,the phase transition temperature of the compound is elevated by 45 K.These compounds exhibit captivating orange light emission when exposed to ultraviolet lamps.This research provides insights into exploring multifunctional materials with orange PL and dielectric switching response and provides proof for halogen substitution strategies to design materials with higher phase transition temperatures.