Synapse transistors based on Li7La3Zr2O12 (LLZO) nanofibers/polyvinyl alcohol (PVA) composite gate dielectric for neuromorphic application

Abstract

As an organic solid electrolyte with an electrical double layer effect, polyvinyl alcohol (PVA) is a promising gate dielectric in artificial synaptic transistors. However, the low ionic conductivity of PVA limits its application. Here, the Li₇La₃Zr₂O₁₂ (LLZO) nanofibers/PVA composite gate dielectric is first introduced to improve its ionic conductivity and construct a high-performance synaptic transistor. After thermogravimetric analysis, the annealing temperature for LLZO precursor solution was verified to be 700 °C and its high crystal structure was verified through X-ray diffraction (XRD), and transmission electron microscopy (TEM). Additionally, the morphology of the nanofibers is observed through a scanning electron microscope (SEM). The LLZO nanofiber/PVA composite gate dielectric is then developed with high light transmittance and electric insulation. Based on it, a synapse transistor with high performance successfully simulated synaptic functions including excitatory post-synaptic current (EPSC), pair-pulse facilitation (PPF), high (low)-pass filtering, logic function and Pavlovian experiments. It is worth noting that the pair-pulse facilitation simulated by this device has a high pair-pulse facilitation coefficient of 1.89 even at a low frequency (1 Hz). This work is a positive exploration to achieve high performance synapse transistors.