Implementation of Photosynaptic and Electrical Memory Functions in Organic Nano-Floating-Gate Transistors via a Perovskite-Nanocrystal-Based Nanocomposite Tunneling Layer

An organic nano-floating-gate transistor (ONFGT) with both photosynaptic and electrical memory functions is developed using a perovskite (CsPbBr₃) NC-insulating polymer (polystyrene; PS) nanocomposite and CsPbBr₃ NCs as the tunneling and floating gate layers, respectively. The introduction of the CsPbBr₃ NCs–PS nanocomposite layer improves the photoresponsivity of the ONFGT under ultraviolet–visible irradiation, resulting in an increase in both the photocurrent and the light-to-dark current ratio by 10⁻⁸ A and 10⁴ orders of magnitude, respectively. It also exhibits high responsivity (0.804 A W⁻¹) and external quantum efficiency (249.3%) under 400 nm irradiation. Furthermore, the photosynaptic characteristics of the ONFGT under visible-light irradiation are investigated. To mimic biological nervous systems, the photocurrent of the device is dynamically modulated by varying the light intensity and duration. Notably, an increase in synaptic weight is observed under repeated photonic stimulations, as shown by changes in synaptic weight with each light pulse. Also, the ONFGT exhibits excellent nonvolatile memory characteristics in the dark, displaying a hysteresis window value of 2.9 V for a gate double sweep under ±5.0 V. Consequently, the perovskite NCs–insulating polymer nanocomposite tunneling layer is crucial for enabling photoresponsivity and memory characteristics in nano-floating-gate transistors, making them suitable for multifunctional electronic devices.