Large-scale roll-to-roll printed, flexible and stable organic bulk heterojunction photodetector

作者：Tong, Sichao; Yuan, Jun; Zhang, Chujun; Wang, Chunhua; Liu, Baoxing; Shen, Jianqiang; Xia, Huayan; Zou, Yingping; Xie, Haipeng; Sun, Jia; Xiao, Si; He, Jun; Gao, Yongli; Yang, Junliang^*

来源：npj Flexible Electronics, 2018, 2(1): 7.

DOI：10.1038/s41528-017-0020-y

A flexible and stable photodetector shows great potential applications in intelligent wearable devices, health monitoring, and biological sensing. The high-output fabrication of flexible and stable photodetector via the large-scale printing process would accelerate its commercialization. Herein, a high performance, flexible organic bulk heterojunction (BHJ) photodetector with good stability is designed and fabricated via a large-scale roll-to-roll (R2R) micro-gravure printing technique on polyethylene terephthalate (PET) or paper substrate, in which the organic BHJ active layer is structured with [6,6]-phenyl C-61 butyric acid methyl ester (PCBM) and a donor-acceptor copolymer, i.e., employing 4,8-bis(2-ethylhexylthiophene) benzo[1,2-b;3,4-b] dithiophene (BDTT) as the donor unit and 5,8-bis(5-thiophen-2-yl)-6,7-difluoro-2,3-bis(4-ethylhexyloxy-1-mata-luorophenyl) quinoxaline (ffQx) as the acceptor unit (PBDTT-ffQx). The PBDTT-ffQx/PCBM BHJ photodetector shows a broad photoresponse in ultraviolet and visible light, a high detectivity (D*) value up to 6.19x10(11) Jones, and an excellent I-photo/I-dark as high as 5.6x10(2). It exhibits excellent flexibility and stability. Its performance parameters could maintain over 80% of original values after bending 10,000 cycles or exposing in ambient condition (humidity similar to 50%, temperature similar to 30 degrees C) for 50 days without any encapsulation. More importantly, the R2R micro-gravure printed PBDTT-ffQx/PCBM BHJ active layer is great homogeneous, and the responsivity (R) values of photodetector arrays show a very narrow distribution. The research results show that a high-performance PBDTT-ffQx/PCBM BHJ photodetector with well reliability and reproducibility can be fabricated via the R2R micro-gravure printing technique, which provides an available strategy for fabricating large-area and flexible electronic and optoelectronic devices. R2R printing: organic devices closer to commercializationRoll-to-roll printing is getting close to the large-scale fabrication of reliable and stable state-of-the-art organic optoelectronic devices. A collaborative team led by Junliang Yang from Central South University, China presents roll-to-roll (R2R) micro-gravure printing method to fabricate high performance and highly stable organic photodetectors on PET or paper substrates in large scale. They find that the bulk heterojunction structure of PBDTT-ffQx/PCBM, a well-known system for organic solar cell, also works as a high-performance photodetector, showing broadband responsivity, high detectivity, and a high photocurrent to dark current ratio. The performance retains over 80% after 10,000 bending cycles or ambient exposure for 50 days. The printed photodetectors have demonstrated good homogeneity, reliability, stability, and reproducibility, showing the promises for large-scale production of printed organic optoelectronic devices.

• 出版日期2018
• 单位中南大学