High-Performance\nProton Field-Effect Transistor Based\non Two-Dimensional Cd Vacancy-Resided Cd<sub>0.85</sub>PS<sub>3</sub>Li<sub>0.15</sub>H<sub>0.15</sub>

Ion\ntransport is a critical phenomenon underpinning numerous biological,\nphysical, and chemical systems. Proton transistors leveraging proton\ntransport face significant limitations, such as a low on–off\nratio and deficient carrier mobility, which restrict their applicability\nin biological and other scenarios. This study explores the use of\ntwo-dimensional (2D) vacancy-residing transition metal phosphorus\ntrichallcogenide-based membranes as the active layer for proton field-effect\ntransistors. The synthesized Cd<sub>0.85</sub>PS<sub>3</sub>Li<sub>0.15</sub>H<sub>0.15</sub> membrane exhibits a well-organized layered\nstructure and high hydrophilicity, with nanometer-sized interlayers\ncontaining interconnected water networks. These distinct features\nfacilitate proton conduction, leading to a high proton conductivity\nvalue of 0.83 S cm<sup>–1</sup> at 98% relative humidity and\n90 °C, with an activation energy of 0.26 eV. The Cd<sub>0.85</sub>PS<sub>3</sub>Li<sub>0.15</sub>H<sub>0.15</sub>-based proton transistor\ndemonstrates tunability via gate voltage, thereby enabling effective\nmodulation of proton flow across source and drain electrodes. The\ntransistor notably showcases superior switching characteristics, with\nan on/off ratio surpassing 5.51 and a carrier mobility of 8.84 ×\n10<sup>–2</sup> cm<sup>2</sup> V<sup>–1</sup> s<sup>–1</sup>. The underlying mechanism for this performance enhancement\nis attributed to electric-field-induced switching in Cd vacancies.\nThis research boosts the development of highly versatile ionotropic\ndevices by introducing advanced 2D ion-conductive membranes.