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X-ray photoemission spectroscopy (XPS) has been used to examine the interaction between Au and HfS 3 at the Au/HfS 3 interface. XPS measurements reveal dissociative chemisorption of O 2 , leading to the formation of an oxide of Hf at the surface of HfS 3 . This surface hafnium oxide, along with the weakly chemisorbed molecular species, such as O 2 and H 2 O, are likely responsible for the observed p-type characteristics of HfS 3 reported elsewhere. HfS 3 devices exhibit n-type behaviour if measured in vacuum but turn p-type in air. Au thickness-dependent XPS measurements provide clear evidence of band bending as the S 2p and Hf 4f core-level peak binding energies for Au/HfS 3 are found to be shifted to higher binding energies. This band bending implies formation of a Schottky-barrier at the Au/HfS 3 interface, which explains the low measured charge carrier mobilities of HfS 3 -based devices. The transistor measurements presented herein also indicate the existence of a Schottky barrier, consistent with the XPS core-level binding energy shifts, and show that the bulk of HfS 3 is n-type. 

The prevalence of anion‐cation contacts in biomolecular recognition under aqueous conditions suggests that ionic interactions should dominate the binding of anions in solvents across both high and low polarities. Investigations of this idea using titrations in low polarity solvents are impaired by interferences from ion pairing that prevent a clear picture of binding. To address this limitation and test the impact of ion‐ion interactions across multiple solvents, we quantified chloride binding to a cationic receptor after accounting for ion pairing. In these studies, we created a chelate receptor using aryl‐triazole CH donors and a quinolinium unit that directs its cationic methyl inside the binding pocket. In low‐polarity dichloromethane, the 1 : 1 complex (logK_1 : 1~ 7.3) is more stable than neutral chelates, but fortuitously comparable to a preorganized macrocycle (logK_1 : 1~ 6.9). Polar acetonitrile and DMSO diminish stabilities of the charged receptor (logK_1 : 1~ 3.7 and 1.9) but surprisingly 100‐fold more than the macrocycle. While both receptors lose stability by dielectric screening of electrostatic stability, the cationic receptor also pays additional costs of organization. Thus even though the charged receptor has stronger binding in apolar solvents, the uncharged receptor has more anion affinity in polar solvents.