Monolayer MoS₂ is a direct band gap semiconductor with large exciton binding energy, which is a promising candidate for the application of ultrathin optoelectronic devices. However, the optoelectronic performance of monolayer MoS₂ is seriously limited to its growth quality and carrier mobility. In this work, we report the direct vapor growth and the optoelectronic device of vertically-stacked MoS₂/MoSe₂ heterostructure, and further discuss the mechanism of improved device performance. The optical and high-resolution atomic characterizations demonstrate that the heterostructure interface is of high-quality without atomic alloying. Electrical transport measurements indicate that the heterostructure transistor exhibits a high mobility of 28.5 cm²/(V·s) and a high on/off ratio of 10⁷. The optoelectronic characterizations prove that the heterostructure device presents an enhanced photoresponsivity of 36 A/W and a remarkable detectivity of 4.8 × 10¹¹ Jones, which benefited from the interface induced built-in electric field and carrier dependent Coulomb screening effect. This work demonstrates that the construction of two-dimensional (2D) semiconductor heterostructures plays a significant role in modifying the optoelectronic device properties of 2D materials.

Optoelectronic synaptic devices integrating light‐perception and signal‐storage functions hold great potential in neuromorphic computing for visual information processing, as well as complex brain‐like learning, memorizing, and reasoning. Herein, the successful growth of MoS₂ monolayer arrays assisted by gold nanorods guided precursor nucleation is demonstrated. Optical, spectral, and morphology characterizations of MoS₂ prove that arrayed flakes are homogeneous monolayers, and they are further fabricated as optoelectronic devices showing featured photocurrent loops and stable optical responses. Typical synaptic behaviors of photo‐induced short‐term potentiation, long‐term potentiation, and paired pulse facilitation are recorded under different light stimulations of 450, 532, and 633 nm lasers at various excitation powers. A visual sensing system consisting of 5 × 6 pixels is constructed to simulate the light‐sensing image mapped by forgetting curves in real time. Moreover, the system presents the ability of utilizing associated images to restore vague and incomplete memories, which successfully mimics human intelligent behaviors of association memory and logical reasoning. The work emulates the brain‐like artificial intelligence using arrayed 2D semiconductors, which paves an avenue to achieve smart retina and complex brain‐like system.

The development of optoelectronic devices requires breakthroughs in new material systems and novel device mechanisms, and the demand recently changes from the detection of signal intensity and responsivity to the exploration of sensitivity of polarized state information. Two-dimensional (2D) materials are a rich family exhibiting diverse physical and electronic properties for polarization device applications, including anisotropic materials, valleytronic materials, and other hybrid heterostructures. In this review, we first review the polarized-light-dependent physical mechanism in 2D materials, then present detailed descriptions in optical and optoelectronic properties, involving Raman shift, optical absorption, and light emission and functional optoelectronic devices. Finally, a comment is made on future developments and challenges. The plethora of 2D materials and their heterostructures offers the promise of polarization-dependent scientific discovery and optoelectronic device application.