Gate-Tunable Positive and Negative Photoconductance in Near-Infrared Organic Heterostructures for In-Sensor Computing.

The rapid growth of sensor data in the artificial intelligence often causes significant reductions in processing speed and power efficiency. Addressing this challenge, in-sensor computing is introduced as an advanced sensor architecture that simultaneously senses, memorizes, and processes images at the sensor level. However, this is rarely reported for organic semiconductors that possess inherent flexibility and tunable bandgap. Herein, an organic heterostructure that exhibits a robust photoresponse to near-infrared (NIR) light is introduced, making it ideal for in-sensor computing applications. This heterostructure, consisting of partially overlapping p-type and n-type organic thin films, is compatible with conventional photolithography techniques, allowing for high integration density of up to 520 devices cm-2 with a 5 µm channel length. Importantly, by modulating gate voltage, both positive and negative photoresponses to NIR light (1050 nm) are attained, which establishes a linear correlation between responsivity and gate voltage and consequently enables real-time matrix multiplication within the sensor. As a result, this organic heterostructure facilitates efficient and precise NIR in-sensor computing, including image processing and nondestructive reading and classification, achieving a recognition accuracy of 97.06%. This work serves as a foundation for the development of reconfigurable and multifunctional NIR neuromorphic vision systems.

Amphiphilic Diblock Co-polymers Bearing a Cysteine Junction Group: Synthesis, Encapsulation of Inorganic Nanoparticles, and Near-Infrared Photoresponsive Properties.

Encapsulation of inorganic nanoparticles (NPs) in the interfaces of amphiphilic vesicles is a challenging task. The traditional strategy is to use amphiphilic triblock co-polymers, which possess two outer blocks for building the walls and coronas of the vesicles, and one middle NP binding block for localizing NPs at the vesicle interfaces. In this manuscript, we describe the design and synthesis of an amphiphilic diblock co-polymer, that is, PEG-SH-b-PS (PEG=poly(ethylene glycol), PS=polystyrene) bearing a cysteine junction with one free pendant thiol group at the center point between the hydrophilic poly(ethylene glycol) block and the hydrophobic polystyrene block. The amphiphilicity-driven self-assembly in aqueous solution of the pure linear diblock co-polymer PEG-SH-b-PS and the corresponding amphiphilic PEG-SH-b-PS/gold NPs (GNPs) nanocomposites is examined. From TEM observations of the self-assembled samples containing the conjugated GNPs, it can be concluded that most of the GNPs are dispersed at the interfaces of the formed vesicles. In addition, near-infrared (NIR)-absorbing copper monosulfide (CuS) NPs are also encapsulated into the PEG-SH-b-PS vesicles. Due to the photothermal heating effect of the CuS NPs, the corresponding PEG-SH-b-PS/CuSNPs vesicles can disassemble and release the embedded cargos under NIR illumination, which endows this nanocomposite material with potential in biomedical applications, such as cancer imaging, photothermal therapy, and drug delivery.