Nanofiber Production Equipment| Negative Photoconductivity in Nanowires/QDsHeterojunction Network for Neuromorphic VisualPerception

Professor Wang Fengyun from Qingdao University & Professor Zhou Ye from Shenzhen University: Negative Photoconductivity Effect in Metal Oxide Nanowire/Perovskite Quantum Dot Heterojunction Devices

Neuromorphic vision systems integrate image information acquisition, processing and storage, showing significant application potential in intelligent security and healthcare fields. Currently, commercial human vision bionic systems mainly rely on silicon-based CMOS logic circuits to simulate synaptic functions. Compared with traditional silicon-based materials, metal oxide nanowires possess unique advantages including large specific surface area and persistent photoconductivity. However, artificial synaptic devices based on metal oxide nanowires typically only achieve unidirectional photoresponse enhancement, which presents limitations in simulating the hyperpolarization behavior of rod and cone cells, and brings challenges to subsequent image classification and recognition functions.

Recently, Professor Wang Fengyun from Qingdao University and Professor Zhou Ye's team from Shenzhen University published their latest research "Negative Photoconductivity in Nanowires/QDs Heterojunction Network for Neuromorphic Visual Perception" in Advanced Functional Materials. The researchers prepared metal oxide nanowire (IZTO) networks using low-cost electrospinning process, constructed specific heterostructures by loading Cs3Bi2Br9 quantum dots on nanowire surfaces, and ultimately fabricated devices demonstrating negative photoconductivity under UV light. Furthermore, they employed a series of advanced characterization techniques to study carrier dynamic transport processes within the materials. The results indicate that the negative photoconductivity effect is caused by heterojunction-related conductive carrier depletion. Additionally, the device array was used to implement optical signal encryption functions, and the array with tunable conductivity was applied to artificial vision system development, significantly reducing redundant data and noise while improving recognition accuracy from 51% to 99%. This study demonstrates the broad prospects and application potential of photoelectric synaptic devices based on metal oxide nanowires and perovskite heterojunctions in artificial vision systems.

Figure 1: Schematic diagram of the preparation process and material characterization of Cs₃Bi₂Br₉ quantum dot/IZTO nanowire heterojunction devices

Figure 2: Electrical test of Cs₃Bi₂Br₉ quantum dot/IZTO nanowire heterojunction device

Figure 3: Schematic diagram of the built-in electric field direction and band structure of Cs₃Bi₂Br₉ quantum dot/IZTO nanowire heterojunction

Figure 4: The mechanism of the negative photoconductivity effect

Figure 5: Decoding and encoding functions of optical signals based on heterojunction array

Figure 6: Construction of artificial vision system

Paper link: https://doi.org/10.1002/adfm.202504250