Low-voltage protonic/photonic synergic coupled oxide phototransistor

Conventionally, oxide phototransistors operate at high voltage due to the limited electrostatic modulation behaviors of traditional gate dielectrics. In the present work, we report low-voltage driven chitosan-gated indium tin oxide (ITO) phototransistors with protonic/photonic synergic coupling effects. Due to strong proton gating effects of chitosan, the phototransistor can operate at low voltage of below 1.5 V. Under illumination with light wavelength of 400 nm, the phototransistor exhibits high photoresponsivity up to ∼300 A/W and optical gain up to ∼5000 at low gate bias of −0.45 V. The photoresponses are related to activation of trapped electrons at the interface, which negatively drifts the threshold voltage. Due to the inherent protonic/photonic synergic coupling effects, the phototransistors also demonstrate synaptic functions, including excitatory postsynaptic current and paired-pulse facilitation. Protonic/photonic synergic coupled oxide phototransistors may have potential applications in portable electronics and visual neuromorphic platforms.