J. Mater. Sci. Technol. ›› 2023, Vol. 135: 46-53.DOI: 10.1016/j.jmst.2022.06.045

• Research Article • Previous Articles     Next Articles

Orientation and mobility control of 4HCB organic film for flexible X-ray detectors with high performance

Meng Xua, Menghua Zhua,*, Dou Zhaoa, Sixin Chena, Shilin Liua, Quanchao Zhanga, Pei Yuana, Binbin Zhanga, Paul Sellinb, Wanqi Jiea, Yadong Xua,*   

  1. aState Key Laboratory of Solidification Processing, MIIT Key Laboratory of Radiation Detection Materials and Devices, and School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an 710072, China;
    bDepartment of Physics, University of Surrey, Guildford GU2 7XH, UK
  • Received:2022-02-18 Revised:2022-06-02 Accepted:2022-06-25 Published:2023-02-01 Online:2022-08-02
  • Contact: *E-mail addresses: mhzhu@nwpu.edu.cn (M. Zhu), xyd220@nwpu.edu.cn (Y. Xu)

Abstract: In comparison to inorganic counterparts, organic semiconducting (OSC) crystalline films are promising for building large-area and flexible ionizing radiation detectors for X-ray imaging or dosimetry due to their tissue equivalence, simple processing and large-scale production accessibility. Fabrication processes, however, hinder the ability to generate aligned and large-area films with high carrier mobility. In this work, the space-confined melt process is used to produce highly orientated 4HCB (4-hydroxycyanobenzene) OSC films with a large area of 15×18 mm2. The out-of-plane direction of the 4HCB film is <001>, and the benzene rings are found to be extensively overlapped inside the in-plane direction, according to the XRD patterns. The film exhibits a high resistivity up to 1012Ω cm, and high hole mobility of 10.62 cm2 V-1 s-1. Furthermore, the 4HCB (80μm-thick film) based X-ray detectors can achieve a sensitivity of 93μC Gyair-1 cm-2 and on/off ratio of 157. The device also shows steady flexibility, with no degradation in detecting function after 100 cycles of bending. Finally, the proposed 4HCB film detectors demonstrated a high-resolution X-ray imaging capability. The imaging of several materials with sharp edges (copper and polytetrafluoroethylene) has been obtained. This work has developed a fast but efficient approach for producing large-area, highly oriented OSC films for high-performance X-ray detectors.

Key words: Organic semiconducting films, Highly oriented, X-ray Detector, X-ray imaging, Wearable detector