Zhang Lei, Liang WanZhen
State Key Laboratory of Physical Chemistry of Solid Surfaces, Collaborative Innovation Center of Chemistry for Energy Materials, Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University , Xiamen, Fujian 361005, People's Republic of China.
J Phys Chem Lett. 2017 Apr 6;8(7):1517-1523. doi: 10.1021/acs.jpclett.6b03005. Epub 2017 Mar 21.
This work aims to explore the intrinsic properties of two-dimensional (2D)-layered perovskites, (PEA)PbI(N) and CsPbI(N), and demonstrating how their structures and properties vary with N. The results reveal that both (PEA)PbI(N) and CsPbI(N) are direct bandgap semiconductors, their band/optical gaps and exciton-binding energies vary linearly with 1/N at N ≥ 3, and the effective masses slowly vary with N. Compared to the bulk phases, the structures of ultrathin (PEA)PbI(N) are more flexible and deformable than CsPbI(N). The giant spin-coupling effect greatly decreases the band gaps of both 2D materials; however, it only induces the spin splitting in the bands of (PEA)PbI(N). This work suggests that the ultrathin 2D materials can be a potential candidate for nano-optoelectronic devices, and that the nanoplates with N ≥ 3 could have similar performances with bulk materials in the carrier migration and exciton separation so that they can be effectively applied in photovoltaic cells.
这项工作旨在探索二维（2D）层状钙钛矿（PEA）PbI（N）和CsPbI（N）的内在特性，并展示它们的结构和性质如何随N变化。结果表明，（PEA）PbI（N）和CsPbI（N）均为直接带隙半导体，在N≥3时，它们的带隙/光学间隙和激子结合能随1/N线性变化，有效质量随N缓慢变化。与体相相比，超薄（PEA）PbI（N）的结构比CsPbI（N）更具柔韧性和可变形性。巨大的自旋耦合效应极大地降低了两种二维材料的带隙；然而，它仅在（PEA）PbI（N）的能带中诱导自旋分裂。这项工作表明，超薄二维材料可能是纳米光电器件的潜在候选材料，并且N≥3的纳米板在载流子迁移和激子分离方面可能具有与体材料相似的性能，从而可以有效地应用于光伏电池。
