(a) Schematic of biological neurons and the electroluminescent synaptic device. (b) EL decay of the synaptic device stimulated by an 8 V electrical spike. The inset is the electrical spike and the corresponding optical power of the EL. (c) Band alignment between the ZnO, Si NCs, and CPB layers under a bias voltage. The dangling-bond-induced deep energy level is indicated by the dashed line. (d) PPF induced by two successive electrical spikes with the interval (Δt) of 5 ms. (e) Optical power of the synaptic device stimulated by 8 V electrical spikes, the number of which changes from 100 to 300. (f) Optical power of the synaptic device under the stimulation of ten successive electrical spikes at the spiking frequencies from 2 Hz to 30 Hz. Reproduced with permission from Ref. [70]. Copyright 2018, Elsevier Ltd.