Interplay of Cation Ordering and Ferroelectricity in Perovskite Tin Iodides: Designing a Polar Halide Perovskite for Photovoltaic Applications.
Owing to its ideal semiconducting band gap and good carrier-transport properties, the fully inorganic perovskite CsSnI3has been proposed as a visible-light absorber for photovoltaic (PV) applications. However, compared to the organic-inorganic lead halide perovskite CH3NH3PbI3, CsSnI3solar cells display very low energy conversion efficiency. In this work, we propose a potential route to improve the PV properties of CsSnI3. Using first-principles calculations, we examine the crystal structures and electronic properties of CsSnI3, including its structural polymorphs. Next, we purposefully order Cs and Rb cations on the A site to create the double perovskite (CsRb)Sn2I6. We find that a stable ferroelectric polarization arises from the nontrivial coupling between polar displacements and octahedral rotations of the SnI6network. These ferroelectric double perovskites are predicted to have energy band gaps and carrier effective masses similar to those of CsSnI3. More importantly, unlike nonpolar CsSnI3, the electric polarization present in ferroelectric (CsRb)Sn2I6can effectively separate the photoexcited carriers, leading to novel ferroelectric PV materials with potentially enhanced energy conversion efficiency.
Frontier Institute of Science and Technology and State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University (XJTU) , Xi' an 710049, People's Republic of China.
Gaoyang
G
Gou
Department of Materials Science and Engineering, Drexel University , Philadelphia, Pennsylvania 19104, United States.
Joshua
J
Young
Frontier Institute of Science and Technology and State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University (XJTU) , Xi' an 710049, People's Republic of China.
Xian
X
Liu
Department of Materials Science and Engineering, Northwestern University , 2220 Campus Drive, Evanston, Illinois 60208-3108, United States.|Materials Science Division, Argonne National Laboratory , Argonne, Illinois 60439, United States.
James M
JM
Rondinelli