Over the past century,ferroelectricity has offered exciting opportunities for fundamental research and device applications.However,most of the discovered excellent ferroelectrics are oxide materials with large band ga...Over the past century,ferroelectricity has offered exciting opportunities for fundamental research and device applications.However,most of the discovered excellent ferroelectrics are oxide materials with large band gaps,limiting their potential for optoelectronics applications.Here using first-principles calculations we identify a new narrow-gap ferroelectric beyond oxides,i.e.,ferroelectric perovskite sulphide BaZrS_(3).Under large compressive strains,BaZrS_(3)can be stabilized into a unique supertetragonal phase with an extraordinary polarization of 67.16μC/cm^(2),which is even stronger than that of conventional oxide ferroelectrics.Excitingly,the supertetragonal BaZrS_(3)exhibits a direct narrow band gap of 1.2 eV and excellent electronic properties.Based on the chemical bonding analysis,we attribute the formation of supertetragonal phase to charge re-ordering in which theπbond overlap along the long〈Zr-S〉bond completely vanishes and the antibonding states of theσbond appear below the Fermi level.Our work provides a conceptual strategy for designing new ferroelectrics for electronic and photovoltaic applications.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.52072059,and 11774044)supported by the Joint Funds of the National Natural Science Foundation of China(Grant No.U1930120)。
文摘Over the past century,ferroelectricity has offered exciting opportunities for fundamental research and device applications.However,most of the discovered excellent ferroelectrics are oxide materials with large band gaps,limiting their potential for optoelectronics applications.Here using first-principles calculations we identify a new narrow-gap ferroelectric beyond oxides,i.e.,ferroelectric perovskite sulphide BaZrS_(3).Under large compressive strains,BaZrS_(3)can be stabilized into a unique supertetragonal phase with an extraordinary polarization of 67.16μC/cm^(2),which is even stronger than that of conventional oxide ferroelectrics.Excitingly,the supertetragonal BaZrS_(3)exhibits a direct narrow band gap of 1.2 eV and excellent electronic properties.Based on the chemical bonding analysis,we attribute the formation of supertetragonal phase to charge re-ordering in which theπbond overlap along the long〈Zr-S〉bond completely vanishes and the antibonding states of theσbond appear below the Fermi level.Our work provides a conceptual strategy for designing new ferroelectrics for electronic and photovoltaic applications.
