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Flexible wide-spectrum image sensor based on quantum dot/nanowire composite nanostructure
Broad-spectrum imaging technology can usually perform complete detection and imaging of environments or objects containing multiple wavelength bands (such as ultraviolet, visible, near-infrared, mid-infrared, far-infrared, etc.). In a complex environment, wide-spectrum imaging technology has great advantages over single-band imaging technology in target detection and recognition due to the ability to obtain information in multiple bands. Therefore, this technology has a wide range of applications in biomedicine, crime investigation, mineral exploration, optical communication and all-weather surveillance. However, traditional wide-spectrum image sensors are usually based on rigid substrates such as silicon-based substrates, which are difficult to bend, have poor impact resistance, and are not easy to carry. With the increasing demand for flexible electronic devices, a variety of flexible sensing devices have been developed one after another, such as flexible temperature sensors, pressure sensors, and gas sensors. Therefore, the development of flexible wide-spectrum image sensors is important to meet people's diverse applications. Demand is important. Recently, Shen Guozhen's group from the State Key Laboratory of Superlattices, Institute of Semiconductors, Chinese Academy of Sciences used a two-step vapor deposition method to modify the surface of wide-bandgap n-type Zn2SnO4 (~3.6 eV) nanowires with narrow-bandgap p-type SnS (~1.3 eV) ) quantum dots, and a flexible UV-Vis-NIR wide-spectrum image sensor was successfully developed using a flexible PET plastic film as a substrate. The study found that, compared with pure Zn2SnO4 nanowire devices, SnS quantum dot-decorated Zn2SnO4 nanowire devices have higher ultraviolet response and broadened spectral response range to the near-infrared, which is mainly due to the interaction between Zn2SnO4 nanowires and SnS quantum dots. The quasi-type II heterojunction formed between them and the narrow band gap of SnS quantum dots. Since the device is fabricated on a flexible PET film substrate, and the Zn2SnO4 nanowires have good toughness due to their ultra-high aspect ratio and a radius of curvature as small as micron, the device has excellent bendability and mechanical stability, no obvious performance degradation occurred even after 5000 bending cycles. Under bending conditions, the fabricated flexible broad-spectrum image sensor can clearly identify the target pattern composed of red and white light, indicating its application potential in future flexible broad-spectrum imaging. This work provides a new design idea and feasible process for obtaining high-performance flexible wide-spectrum image sensors. A related article is published online in Advanced Functional Materials (DOI: 10.1002/adfm.201705389).
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