posted on 2020-01-28, 15:40authored byHan-Yue Zhang, Chun-Li Hu, Zhao-Bo Hu, Jiang-Gao Mao, You Song, Ren-Gen Xiong
Due
to the intriguing chemical variability and structure–property
flexibility, molecular materials with striking multifunctional characteristics,
including tunable physical, chemical, optical, and electronic properties,
have aroused wide attention. Recently, great advances have also been
made in designing molecular ferroelastics with optoelectronic properties.
However, the band gaps of the most typical ferroelastics are far in
excess of 2.0 eV, which severely hinder their further applications.
And this corresponds to the inherent incompatibility of ferroelastics.
Herein we report an organometallic compound, ferrocenium tetrachloroferrate
(1), undergoing a ferroelastic phase transition at 407.7
K with a large spontaneous strain of 0.1088. To the best of our knowledge,
this is the first molecular ferroelastic with such a high Curie temperature
(Tc) and narrow band gap of 1.61 eV. UV–vis
absorption spectra and density-functional theory (DFT) calculation
confirm this band gap. The band gap of 1 is determined
by both the ferrocenium and the tetrachloroferrate components. The
ideal semiconducting characteristic makes a breakthrough in the inherent
incompatibility with ferroelastics. This will inspire an intriguing
and further research in molecular ferroelastics with ideal semiconductor
characteristics and hold great potential for the utilization in optoelectronic
devices, especially the photovoltaic applications.