Selective Release of Excitatory-Inhibitory Neurotransmitters Emulated by Unipolar Synaptic Transistors via Gate Voltage Amplitude Modulation

Organic field-effect transistor (OFET) memory devices are benefiting from their independent gate modulation advantages for hardware implementation of synaptic functionalities. However, the imitation of selective release of excitatory-inhibitory neurotransmitters in a unipolar synaptic OFET is challenging due to the unbalanced mobile carrier concentration. Here, a p-type synaptic OFET memory with CsPbBr3 quantum dots (QDs) as nano-floating gates (NFGs) is developed, which can emulate both the excitatory-inhibitory responses of the biological synapse and their reconfigurable nature. By controlling the offset difference between stimulus voltage and reading voltage, the concomitant and independently expressed excitatory and inhibitory responses are successfully implemented in a negative gate modulation manner, but without introducing an ambipolar semiconductor or additional optical terminal. This reconfigurable modulation is ascribed to the dynamic competition between external electric field and built-in electric field assisted by charge trapping in shallow traps. The proposed gate voltage-offset method can be generally adapted to other unipolar synaptic OFETs. These results provide insight into OFET memory devices for building neuromorphic hardware elements with tailorable synaptic plasticity.