Neuromorphic Device Based on Solution-Processed WSe₂ Nanoflake Synaptic Transistors

Significant progress has been made in developing artificial synapses using transition metal dichalcogenides (TMDs)-based neuromorphic devices, but solution-processable TMDs remain underexplored, especially in utilizing intrinsic defects for synaptic functions. Here, we prepared electrochemically-exfoliated WSe2 nanoflakes with Se vacancies that enable charge trapping and detrapping. Using a solution-processed approach, we fabricated a high-performance WSe2 synaptic transistor with a large memory window, a significant trap density of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5\times 10^{{12}}$ </tex-math></inline-formula> cm<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${}^{-{2}}$ </tex-math></inline-formula>, and high operating stability. This synaptic transistor also successfully mimics various synaptic behaviors such as potentiation and depression, spike-voltage-dependent plasticity, and spike-number-dependent plasticity. By integrating the device with an infrared ranging sensor, the neuromorphic sensory system achieves 94.7% accuracy in object classification task, demonstrating its potential for advanced sensory processing.