Sulfur vacancy in MoS 2 has been found to have an important in uence on the performance of optoelectronic devices. Here, we study the effect of sulfur vacancy and O 2 adsorption on the electronic and optical properties in the two-dimensional ferroelectric CuInP 2 S 6 . It is revealed that a defect state appears at the top of valence band with the presence of sulfur vacancy. However, when O 2 is chemisorbed at sulfur vacancy, the defect state disappears. The variation of charge state and charge transfer are calculated and discussed. Although the ferroelectricity is greatly suppressed with the presence of sulfur vacancy, the ferroelectric state can be recovered when the O 2 is adsorbed. Within the framework of GW + BSE method, the optical absorption edge of CuInP 2 S 6 monolayer exhibits a red-shift for the presence of sulfur vacancy and further O 2 adsorption gives rise to a blue-shift of the spectrum. Our ndings have shown an effective way to improve the functionality of two-dimensional ferroelectrics via defect engineering.

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A series of novel copillar [5]arenes 1a-1f containing different substituents were synthesized. And their complexation with two types of guests was investigated. For symmetrical guests, 1,4-dibromobutane (DBB) could thread in the cavity of copillar [5]arenes to form inclusion complexes. But for the unsymmetrical guests, copillar-[5]arene 1f bearing 4-(naphthalen-1-yloxy)butoxy could not complex with sec-butyl iodide (SBI) and sec-butyl bromide (SBB) at all, while 1f showed weak interaction with sec-butylamine•HCl (SBA) outside the cavity. These results indicated that the modified group of copillar [5]arene and the symmetry of guest played an important role in the complexation model and selectivity.

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