Inversion symmetry-broken CuBO2 delafossite through anionic site doping for improved piezoelectric composites with PVDF and its application in nanogenerators and optoelectronic neuromorphic computing†

Abstract

Currently, self-charging photodetectors are paving the way for future investigations into energy-autonomous electronics, which are expected to facilitate highly efficient applications in memory storage, compact portable devices, photonic neuromorphic computing and optoelectronic systems. In the present study, we developed multifunctional, flexible PCSB composites for use in self-powered piezoelectric sensors and photonic neuromorphic computing by utilizing the synergistic effect of strongly light-activated CuBO_2−xS_x and PVDF (PCSB). The optimized piezoelectric nanogenerator (PNG 3), based on PCSB 3, produced a significant electrical output (V_OC ∼21.8 V and I_SC ∼0.42 μA) under a 4 kHz frequency and 6.1 MPa pressure. PNG 3 demonstrated a peak output power of 0.96 μW cm⁻² when subjected to a resistance of 0.1 GΩ. The optimized devices (PNG 3) effectively harvested energy from various physiological movements, enabling sustainable power generation. Furthermore, the PCSB composite was used to fabricate optoelectronic synaptic device for neuromorphic computing. The excellent photosensitive properties of the CuBO_2−xS_x material enabled the device to operate at an extremely low voltage and achieve low energy consumption per synaptic event. Owing to the efficient separation and transport of photogenerated carriers, facilitated by the conductive CuBO_2−xS_x material, the photoelectric performance was dramatically enhanced. Additionally, the proposed synaptic devices can effectively simulate the characteristics of biological synaptic activity, including excitatory postsynaptic current (EPSC), paired-pulse facilitation (PPF), short-/long-term plasticity and “learning experience” behavior, under UV-light excitation. Notably, the synaptic device also functioned as an AND/OR gate, enabling in-memory logic operations.