Narrow bandgap ferroelectrics are emerging as critical components for assembling high-performance optoelectronic devices with a broadband spectral response,yet integrating narrow bandgap and robust ferroelectricity in...Narrow bandgap ferroelectrics are emerging as critical components for assembling high-performance optoelectronic devices with a broadband spectral response,yet integrating narrow bandgap and robust ferroelectricity in a single-phase material system remains a huge challenge.Herein,we report a narrow bandgap improper molecular ferroelectric,(DMAPA)BiI5(1;DMAPA=dimethylaminopropyl ammonium),which has a bandgap of 1.94 eV and a spontaneous polarization(Ps)value of 1.38μC cm^(−2).It is notable that 1 exhibits unusual dielectric bistability near its Curie temperature(Tc)=372 K,along with only quite small variation in dielectric constants.This characteristic of improper ferroelectricity endows 1 with large pyroelectric figures-of-merit.Strikingly,light-induced change of its electric Ps leads to ultraviolet-to-near-infrared pyroelectricity in a wide spectral region(266–980 nm),thus achieving broadband self-powered photoactivities.High-quality thin films of 1 fabricated via a spin-coating process also exhibit excellent light-induced pyroelectric effects.The integration of photoactivities in narrow bandgap improper ferroelectrics offers a promising pathway toward scalable broadband optoelectronic device application.展开更多
基金supported by NSFC(22125110,U23A2094,22205233,22305248 and U21A2069)the Natural Science Foundation of Fujian Province(2023J02028 and 2025J01247)+2 种基金the Fujian Science&Technology Innovation Laboratory for Optoelectronic Information of China(2021ZR126)the Postdoctoral Fellowship Program of CPSF(GZB20240746)the China Postdoctoral Science Foundation(2024T170923 and 2024M753233).
文摘Narrow bandgap ferroelectrics are emerging as critical components for assembling high-performance optoelectronic devices with a broadband spectral response,yet integrating narrow bandgap and robust ferroelectricity in a single-phase material system remains a huge challenge.Herein,we report a narrow bandgap improper molecular ferroelectric,(DMAPA)BiI5(1;DMAPA=dimethylaminopropyl ammonium),which has a bandgap of 1.94 eV and a spontaneous polarization(Ps)value of 1.38μC cm^(−2).It is notable that 1 exhibits unusual dielectric bistability near its Curie temperature(Tc)=372 K,along with only quite small variation in dielectric constants.This characteristic of improper ferroelectricity endows 1 with large pyroelectric figures-of-merit.Strikingly,light-induced change of its electric Ps leads to ultraviolet-to-near-infrared pyroelectricity in a wide spectral region(266–980 nm),thus achieving broadband self-powered photoactivities.High-quality thin films of 1 fabricated via a spin-coating process also exhibit excellent light-induced pyroelectric effects.The integration of photoactivities in narrow bandgap improper ferroelectrics offers a promising pathway toward scalable broadband optoelectronic device application.
