2D Porous Organic Polymer Sheet/Graphene Hybrid for Efficient UV-Sensitive Detections and Self-Restoring Flexible Synaptic Devices With 10,000 s Ultralong Memory

Abstract

Flexible UV-sensitive photodetectors and optoelectronic synapses are highly desired in numerous sensing areas and neuromorphic computations. Herein, the large-size, flat, and continuous sheet of polyamic acid (PAA), a two-dimensional (2D) porous organic polymer (POP), was synthesized at the liquid/liquid interface. Combining with graphene (G), the hybrids demonstrate efficient UV-selective photodetection. On the soft substrate of polyethylene glycol terephthalate (PET), the UV-selective detecting ability is retained even under 90° bending and after 20,000 bending cycles, indicating the remarkable flexibilities. And our PAA/G/PET devices exhibit self-healing capability via a simple thermal annealing at 45°C. The remarkable flexibilities can be attributed to the high mechanical strength of 2D covalent-bonded backbones of PAA and G, the adaptive porous connections, and reversible broken/reformation of the large number of hydrogen bonds in PAA. Furthermore, the PAA/G/PET devices can mimic the functions of biosynapse very well, including paired-pulse facilitation, short-term plasticity (STP) and long-term plasticity (LTP), transition of STP to LTP, spike time, number, and intensity-dependent plasticity. With this optoelectronic synapse, the human brain-like process and wireless communications are realized. The memory time can achieve 10,000 s after 45 s learning. And the synaptic functions persist at the bending angle of 90°. The results in this work provide valuable support for developing flexible wavelength-selective photodetectors and artificial synapses with 2D POPs and their hybrid films.

Keywords

artificial synapse / flexible photodetectors / graphene / polyamic acid / porous organic polymer / self-healing

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