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Abstract The prevailing von Neumann bottleneck has demanded alternatives capable of more efficiently executing massive data in state‐of‐the‐art digital technologies. Mimicking the human brain's operational principles, various artificial synapse devices have emerged, whose fabrications generally require high‐temperature complementary metal‐oxide‐semiconductor (CMOS) processes. Herein, centimeter‐scale tellurium (Te) films‐based optoelectronic synaptic devices are explored by a back‐end‐of‐line (BEOL) compatible low‐temperature (200 °C) chemical vapor deposition (CVD). The CVD‐grown Te films exhibit prominent semiconducting properties such as broadband photo‐responsiveness accompanying a large degree of mechanical deformability. These characteristics coupled with their scalable manufacturability realize a comprehensive set of optically‐stimulated synaptic plasticity; i.e., excitatory postsynaptic current (EPSC), paired‐pulse facilitation (PPF), and short‐to‐long‐term memory conversion, all of which are well preserved even under severe mechanical deformations. A variety of proof‐of‐concept applications for artificial neural networks (ANNs) are demonstrated employing these deformation‐invariant synaptic features; i.e., high‐accuracy (≈90%) pattern recognition, associative learning, and machine learning‐implemented visual perception. The fundamental mechanism for the synaptic operations is discussed in the context of their persistent photoconductivity (PPC) and its associated memory effect. This study highlights high promise of low‐temperature processable semiconductors for emergent neuromorphic architectures with various form factors beyond the conventional CMOS strategy. 

Abstract In-plane anisotropic two-dimensional (2D) materials exhibit in-plane orientation-dependent properties. The anisotropic unit cell causes these materials to show lower symmetry but more diverse physical properties than in-plane isotropic 2D materials. In addition, the artificial stacking of in-plane anisotropic 2D materials can generate new phenomena that cannot be achieved in in-plane isotropic 2D materials. In this perspective we provide an overview of representative in-plane anisotropic 2D materials and their properties, such as black phosphorus, group IV monochalcogenides, group VI transition metal dichalcogenides with 1T′ and T_dphases, and rhenium dichalcogenides. In addition, we discuss recent theoretical and experimental investigations of twistronics using in-plane anisotropic 2D materials. Both in-plane anisotropic 2D materials and their twistronics hold considerable potential for advancing the field of 2D materials, particularly in the context of orientation-dependent optoelectronic devices.