Feng Xin, Peng Xingliang, Peng Baixin, Li Zexin, Huang Wentao, Yang Sijie, Pei Ke, Sun Zongdong, Huang Fuqiang, Li Huiqiao, Shuai Zhigang, Zhai Tianyou
State Key Laboratory of Materials Processing and Die & Mould Technology and School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, People's Republic of China.
MOE Key Laboratory of Organic OptoElectronics and Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing 100084, People's Republic of China.
J Am Chem Soc. 2021 Dec 8;143(48):20192-20201. doi: 10.1021/jacs.1c08030. Epub 2021 Nov 15.
Strong intermolecular interactions in 2D organic molecular crystals arising from π-π stacking have been widely explored to achieve high thermal stability, high carrier mobility, and novel physical properties, which have already produced phenomenal progress. However, strong intermolecular interactions in 2D inorganic molecular crystals (2DIMCs) have rarely been investigated, severely limiting both the fundamental research in molecular physics and the potential applications of 2DIMCs for optoelectronics. Here, the effect of strong intermolecular interactions induced by unique short intermolecular Se-Se and P-Se contacts in 2D α-PSe nanoflakes is reported. On the basis of theoretical calculations of the charge density distribution and an analysis of the thermal expansion and plastic-crystal transition, the physical picture of strong intermolecular interactions can be elucidated as a higher charge density between adjacent PSe molecules, arising from an orderly and close packing of PSe molecules. More importantly, encouraged by the strong intermolecular coupling, the in-plane mobility of α-PSe nanoflakes is first calculated with a quantum nuclear tunneling model, and a competitive hole mobility of 0.4 cm V s is obtained. Our work sheds new light on the intermolecular interactions in 2D inorganic molecular crystals and is highly significant for promoting the development of molecular physics and optoelectronics.
二维有机分子晶体中由π-π堆积产生的强分子间相互作用已被广泛研究，以实现高热稳定性、高载流子迁移率和新颖的物理性质，并且已经取得了显著进展。然而，二维无机分子晶体（2DIMCs）中的强分子间相互作用却很少被研究，这严重限制了分子物理的基础研究以及2DIMCs在光电子学中的潜在应用。在此，报道了二维α-PSe纳米片中独特的短分子间Se-Se和P-Se接触所诱导的强分子间相互作用的影响。基于电荷密度分布的理论计算以及对热膨胀和塑性晶体转变的分析，强分子间相互作用的物理图像可被阐明为相邻PSe分子之间更高的电荷密度，这源于PSe分子的有序紧密堆积。更重要的是，受强分子间耦合的鼓舞，首次用量子核隧穿模型计算了α-PSe纳米片的面内迁移率，得到了0.4 cm V s的竞争空穴迁移率。我们的工作为二维无机分子晶体中的分子间相互作用提供了新的见解，对推动分子物理和光电子学的发展具有重要意义。
