Recently, a new progress in flexible ultraviolet (UV) imaging technology has been achieved by the concerted efforts of Prof. SHEN Guozhen’s Group in Institute of Semiconductors, Chinese Academy of Sciences, with their collaborators in Hong Kong University of Science and Technology.

As an important application of UV light, UV imaging technology have triggered enormous interest because of their wide applications in crime investigation, oil spill detecting, fire monitoring, and electrical power line inspection. However, conventional UV image sensors are usually based on rigid substrates, which are fragile, inflexible, weighty and high-cost. These defects limit the application of UV image sensors in many fields. Compared with conventional UV image sensors, flexible UV image sensors possess the attractive features of being flexible, light-weight, wearable and low-cost, which can form a complementation with conventional UV image sensors to satisfy the diversified needs of modern society.

In this context, Dr. LI Ludong and Assistant Prof. LOU Zheng in the team fabricated successfully a kind of high-performance flexible UV image sensor based on ZnO quantum dots (QDs) decorated ZTO nanowires (NWs). The device was fabricated on the flexible polyethylene terephthalate (PET) substrate, which displayed outstanding flexibility, electrical stability and folding endurance.

Duo to the rational band engineering at the QD/NW interface which results in effective separation of electron-hole pairs, the device showed ultrahigh specific detectivity (up to 9.0 × 10¹⁷ Jones), photoconductive gain (up to 1.1 × 10⁷) and high response speed (47 ms).

In addition, the corresponding device simulations were also carried out, which were consistent with the experimental data. The flexible UV image sensor can detect and reproduce the UV image under bending condition, indicating the tremendous application potential in future flexible UV imaging technology.

This work provides a new design idea and the feasibility process for the fabrication of high-performance flexible UV image sensors. With further research and improvement, the higher pixel integration can be achieved and a life with the application of flexible UV image sensors may be near.

This work entitled “ZnO Quantum Dot Decorated Zn₂SnO₄ Nanowire Heterojunction Photodetectors with Drastic Performance Enhancement and Flexible Ultraviolet Image Sensors” was recently published in ACS Nano (DOI: 10.1021/acsnano.7b00749). It was supported by the National Natural Science Foundation of China (Nos. 61377033, 61625404, 61574132, 61504136), Beijing Natural Science Foundation (No. 4162062) and the Key Research Program of Frontier Sciences, CAS (No. QYZDY-SSW-JWC004).

The full text link: http://pubs.acs.org/doi/pdf/10.1021/acsnano.7b00749.