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Abstract Differing from its bulk counterparts, atomically thin two-dimensional transition metal dichalcogenides that show strong interaction with light are considered as new candidates for optoelectronic devices. Either physical or chemical strategies can be utilized to effectively tune the intrinsic electronic structures for adopting optoelectronic applications. This review will focus on the different tuning strategies that include its physics principles, in situ experimental techniques, and its application of various optoelectronic devices.

Two-dimensional (2D) magnets have raised enormous attention because of their stable long-range magnetic orders and anomalous magnetic physics at 2D limits. Spin glass states are normally discovered in disordered systems with spin frustration, which are rarely found in 2D crystalline materials. Here, the chemical vapor-deposited rhombohedral Cr2Se3 nanosheets could be grown down to a thickness of 1.9 nm, which have shown a hard magnetism of large coercivity of 1.5 kOe and exhibited thermal irreversibility. A spin glass state with a freezing temperature of 28 K can be estimated from an alternating-current magnetic susceptibility survey, in which unambiguous magnetic response evidence of a spin glass state in crystalline Cr2Se3 nanosheets was shown. An extracted short relaxation time of 10–13 s and atomic magnetic frustration that were confirmed by neutron diffraction could strongly suggest the spin glass state with an atomically short-range magnetic order in the Cr2Se3 nanosheets.

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A local large-scale reversible phase transition of MoTe2 film was accomplished through the heat treatment.