Probing the Edges between Stability and Degradation of a Series of ZnSe-Based Layered Hybrid Semiconductors

The discovery of layered materials with potentially unique electrical and chemical properties has become a major focus of materials research in the past decade. II-VI layered hybrids (LHs) are a family of ligand-protected layered materials capable of isolation in few-layer form and possess emissive and electronic properties of potential relevance to semiconductor device technologies. We showed previously that, akin to black phosphorus (BP) and transition metal dichalcogenides (TMDCs), II-VI LHs are sensitive to ambient atmospheric conditions. However, the causes for degradation of these ligand-protected materials remain unclear. Using ZnSe-based LHs, we show herein that the stability of these materials is related to the length and chemistry of the organic ligands coordinated to the LH surfaces. Furthermore, exposure to isotopically enriched H218O and 18O2 reveals that H2O and O2 are both reactants contributing to ZnSe-LH degradation. An H2O-initiated degradation pathway is proposed and is supported by density functional theory (DFT) calculations. Our findings contribute to the discovery of protection strategies for layered materials and elucidate a degradation pathway that may also be applicable to other layered materials.