UV-sensing organic phototransistor memory devices with a doped organic polymer electret composed of triphenylamine-based aggregation-induced emission luminogens

• Published in: Journal of materials chemistry. C, Materials for optical and electronic devices Materials for optical and electronic devices, 2019, Vol.7 (35), p.1114-1121
• Main Authors: Huang, Teng-Yung, Chen, Chia-Hui, Lin, Chia-Chi, Lee, Yu-Jung, Liu, Cheng-Liang, Liou, Guey-Sheng
• Format: Article
• Language: English
• Subjects: Agglomeration; Data storage; Electrets; Electric fields; Endurance; Excitons; Fluorescence; Memory devices; Optimization; Photoelectric effect; Photoelectric emission; Photoexcitation; Photosensitivity; Phototransistors; Polyimide resins; Threshold voltage
• ISSN: 2050-7526; 2050-7534
• DOI: 10.1039/c9tc03607e

This paper reports a UV-sensing organic field-effect phototransistor with a stacked pentacene channel and a doped aggregation-enhanced emission (AIE)-fluorescent electret for potential applications, such as photomemory storage and photodetectors. It is found that the emission of the photoirradiated doped electret ( PA-SM X and PI-SM X ) layer can be manipulated at various doping levels, which can be further absorbed by the photoactive pentacene channel. These photogenerated excitons can be separated, and the electrons can be trapped into the electret layer in the presence of gate voltage bias. Therefore, the photoinduced programming and electric field-driven erasing effects of the designed memory device based on doped electrets exhibit optimal photomemory performance with a memory window (MW) of 37.2 V and a reliable retention time over 10000 s with good cyclic endurance. The photodetection can also be modulated by the illumination power intensity, which reflects a photosensitivity ( S ) of 1.92 10 6 and a photoresponsivity ( R ) of 45 A W 1 for organic phototransistors with the PI-SM5 doped electret at a photoexcitation intensity of 720 W cm 2 at 365 nm. The photoresponse following the change in the threshold voltage and photocurrent correlate well with the spectroscopic results and provide further understanding and optimization of organic phototransistor memory devices. The UV-sensing OFET memories with enhanced memory performance are developed by introducing the AIEgen-doped electret which could obtain better spectral overlap between the emission of doped electrets and the absorption of pentacene.