Liao Cheng-Sheng, Yu Zhuo-Liang, He Peng-Bin, Liu Biao, Zeng Ruosheng, Wan Qiang, Cai Meng-Qiu
Key Laboratory for Micro/Nano Optoelectronic Devices of Ministry of Education & Hunan Provincial Key Laboratory of Low-Dimensional Structural Physics and Devices, School of Physics and Electronics, Hunan University, Changsha 410082, China.
Hunan Key Laboratory for Super-microstructure and Ultrafast Process, School of Physics and Electronics, Central South University, Changsha 410083, Hunan, China.
J Colloid Interface Sci. 2021 Sep;597:233-241. doi: 10.1016/j.jcis.2021.03.121. Epub 2021 Mar 27.
Ferroelectric polarizationhas been considered to be an key factor to tune the structural and photoelectric properties of perovskites and their heterostructures. While there has been growing researches made in the novel phenomena originating from interface formed between oxide perovskites, the effects of ferroelectric polarization on the electronic properties of halide perovskites and their heterostructures are rarely studied. Herein, by using first-principles calculations, all-inorganic halide perovskite heterostructure composed of 3D perovskite tetragonal CsPbBr and 2D Ruddlesden-Popper (RP) perovskite CsPbICl is constructed for disclosing the relationship between the intrinsic polarization of tetragonal CsPbBr and electronic band structure of heterostructure. Cs atoms and Pb atoms of tetragonal CsPbBr in heterostructure are artificially moved away from the equivalent centers to simulate increased polarization. Our results show that with the spontaneous polarization of tetragonal CsPbBr increasing, the bandgap of heterostructure decreases, and the band alignment switches from staggered type-II to broken-gap type-III. Moreover, large cation-anion displacements along z-direction in tetragonal CsPbBr can be observed when tensile strains (≥5%) are applied, indicating a increased ferroelectric polarization, which also facilitates the decreasing of bandgap in heterostructure and the type-II-type-III transition of band alignment. Our study suggests that control over the polarization of ferroelectric materials is of great importance to tune the photoelectric properties of perovskite-based devices.
铁电极化被认为是调节钙钛矿及其异质结构的结构和光电性能的关键因素。虽然对源自氧化物钙钛矿之间形成的界面的新现象的研究越来越多，但铁电极化对卤化物钙钛矿及其异质结构的电子性质的影响却很少被研究。在此，通过第一性原理计算，构建了由3D钙钛矿四方相CsPbBr和2D Ruddlesden-Popper（RP）钙钛矿CsPbICl组成的全无机卤化物钙钛矿异质结构，以揭示四方相CsPbBr的固有极化与异质结构的电子能带结构之间的关系。异质结构中四方相CsPbBr的Cs原子和Pb原子被人为地从等效中心移开，以模拟增加的极化。我们的结果表明，随着四方相CsPbBr的自发极化增加，异质结构的带隙减小，能带排列从交错的II型转变为破隙的III型。此外，当施加拉伸应变（≥5%）时，可以观察到四方相CsPbBr中沿z方向的大阳离子-阴离子位移，这表明铁电极化增加，这也有利于异质结构中带隙的减小和能带排列的II型-III型转变。我们的研究表明，控制铁电材料的极化对于调节基于钙钛矿的器件的光电性能非常重要。
