Self-powered wavelength-selective bipolar dual-mode optoelectronic device based on a SnO2/CsBi3I10–IR820 heterojunction

Achieving self-powered dual-mode optoelectronic devices that integrate fast photodetection with optoelectronic synaptic functionality remains challenging because signal sensing and memory rely on different response dynamics. Here, a self-powered wavelength-selective bipolar dual-mode optoelectronic device based on a SnO2/CsBi3I10–IR820 heterojunction is fabricated. At zero bias, the device exhibits a positive and rapid photodetection response under 650 nm illumination, with a responsivity of 0.18 A/W and a specific detectivity of 1.2 × 1013 Jones. Under 820 nm illumination, the photocurrent polarity reverses, and the device mimics optoelectronic synaptic behaviors, including short-term and long-term plasticity. The wavelength-selective bipolar dual-mode operation is due to the competition between the built-in photovoltaic effect in the SnO2/CsBi3I10–IR820 heterojunction and the photothermoelectric effect introduced by IR820. These results provide a simple strategy for self-powered multifunctional optoelectronic devices with integrated sensing and memory functions.