Abstract
Neuromorphic vision sensors are designed to mimic the human visual system, which allows image recognition with low power computational requirements. Photonic synaptic devices are one of the most viable building blocks for constructing neuromorphic vision sensors. Herein, a photonic synaptic sensor based on an inorganic perovskite quantum dot (QD) embedded InGaZnO (IGZO) thin-film phototransistor is demonstrated. The photodetection wavelength ranges of the transistor can be adjusted by changing the halogen ions (Cl, Br) of the perovskite QDs. Under low intensity 450 and 550 nm illumination, the CsPbBr3 QD embedded phototransistor sensor shows a responsivity of 6.7 × 102 and 4.2 × 10−2 A W−1, respectively. The perovskite QD embedded transistor not only presents high responsivity to visible light, but also features excellent synaptic behavior, including an excitatory postsynaptic current (EPSC), pair-pulse facilitation (PPF), long-term memory, and memory erasure through gate voltage regulation. Moreover, the sensor fabrication process in this work is compatible with conventional photolithography processes. Taking these merits into account, the proposed QD embedded IGZO transistor presents a promising route by which to construct artificial visual sensors with color-distinguishable optical signal sensing and processing.
Highlights
Silicon-based digital image sensors are widely used nowadays, our modern imaging sensor systems are still far from being convergent with the human eye visual system
IGZO transistor embedded with perovskite quantum dots
The X-ray diffraction (XRD) pattern of the perovskite quantum dot (QD) are in accordance with the CsPbBr3 cubic lattices (PDF# 54-0752), as shown in Fig. S1.† The right shi in the XRD diffraction peak of the CsPbClBr2 QDs can be attributed to a decrease in the lattice constant due to the doping of chloride ions.[29]
Summary
The high eld-effect carrier mobility, high transparency, and capability of fabrication on exible substrates makes IGZO a candidate to be utilized in a wide range of applications, from display panels to logic circuits.[10,11] The mobility of the metal oxide semiconductor, IGZO, is higher than that of amorphous silicon, which meets the requirements where large driving current density is needed, such as organic light-emitting diode (OLED) displays.[12,13] with a wide bandgap of 3.5 eV, IGZO is only sensitive to the ultraviolet wavelength region, limiting its application as a visible light sensor.[14]. Previous reports have recently addressed halide perovskite based photonic synapsis, which interestingly emulate both synaptic plasticity and learning processes.[25,26,27,28]. Our device con guration of the perovskite QD embedded IGZO phototransistor features stacks of IGZO/QDs/IGZO in the channel region. This sandwich structure allows QDs to be protected from oxygen, water and organic solvent attack. The stacked layers can be patterned into small devices via conventional photolithography. Short-term plasticity (STP) behavior such as excitatory postsynaptic current (EPSC) and paired-pulse facilitation (PPF) are demonstrated. The transformation from short-term to long-term plasticity (LTP) can be realized by adjusting the shape of the light pulse. Tuning the gate voltage pulse results in an inhibitory postsynaptic current (IPSC), which therea er erases the memory-based current
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
