Journal Article 12038-63-0 2D van der Waals layered materials 7440-15-5 Rhenium Sulfides artificial optoelectronic synapses brain-inspired computing convolutional neural networks flexible artificial synapses multi-valued logic computing negative-differential-resistance persistent photoconductivity effect reconfigurable devices and circuits rhenium disulfide rhenium sulfide ternary devices and circuits van der Waals layered materials