A Potential Sn-Based Hybrid Perovskite Ferroelectric Semiconductor

Ferroelectric semiconductors, combining
semiconduction, spontaneous
polarization, and photoinduced excitation, show great promise to enhance
the performance of solar cells, pressure sensors, and photodetectors.
Particularly, organic–inorganic lead halide perovskite ferroelectrics
have been explored for their prominent carrier transport properties
and structural tunability. However, a high concentration of toxic
Pb is a stumbling block for their further application. Here, we present
a lead-free hybrid perovskite semiconductor, (C4H9NH3)2­(NH3CH3)2Sn3Br10 (1), which exhibits
a large spontaneous polarization of 11.76 μC cm–2 at room temperature. Significantly, 1 presents a spontaneous
polar ordering transition, similar to the better-known perovskite
ferroelectrics, and exhibits ferroelectric phase transition behaviors.
To our best knowledge, 1 is the first example of a Sn-based
hybrid perovskite semiconductor featuring ferroelectric performance.
Mechanistic studies reveal that such ferroelectricity can be attributable
to the synergistic effects of ordering of organic cations and stereochemically
active lone-pair electrons inducing distortion of inorganic octahedra.
This work provides an effective way to explore “green”
ferroelectric semiconductors with potentially enhanced energy conversion
efficiency.