A thousand-state optoelectronic memory for high-precision spatiotemporal encoding

Conventional photodiodes can distinguish subtle illumination variations, but fail to retain information. Conversely, optoelectronic memories can store light information but encounter difficulties in multiple-state storage due to noise from the deexcitation recombination of the photogenerated carriers. Here we develop an optoelectronic memory that can generate a multilevel response to light stimuli and retain the multi-states in a nonvolatile manner. In the designed type-III heterojunction device, electrons flow from high-Fermi-level (Ef) p-type amorphous carbon to low-Ef n-type TiOx, generating an unusual built-in electric field that enhances majority carrier transport. Photogenerated electrons from the oxygen vacancies in TiOx quickly combine with holes from amorphous carbon, effectively reducing deexcitation recombination with charged vacancies and associated noise. The resulting device achieves 1,024 distinguishable optoelectronic memory states without any denoising process, enabling high-precision spatiotemporal information encoding. The thousands of states in optoelectronic memory allows for the emulation raptor vision to perception fast-moving objects. Noise in optoelectronic memories causes harmful overlap of photoconductance states and degrades computing precision. Zhou et al. report an optoelectronic memory that achieves thousands of distinguishable states without denoising, enabling the detection of fast-moving objects.