Chen, Y.-C.Y.-C.ChenLin, Y.-C.Y.-C.LinHsieh, H.-C.H.-C.HsiehHsu, L.-C.L.-C.HsuYang, W.-C.W.-C.YangIsono, T.T.IsonoSatoh, T.T.SatohWEN-CHANG CHEN2021-08-052021-08-05202120507534https://www.scopus.com/inward/record.uri?eid=2-s2.0-85100472893&doi=10.1039%2fd0tc05326k&partnerID=40&md5=a4753f036ff984942bac0104e117d439https://scholars.lib.ntu.edu.tw/handle/123456789/576796We report the synthesis, morphology and photo-memory device applications of a block copolymer (BCP) consisting of poly(9,9-dioctylfluorene) (PFO) and polystyrene (PS). Three BCPs were designed with various PS contents to manipulate the structure-performance relationship of the polymer electrets in a photonic field-effect transistor-type (FET) memory device. The memory device using the BCP electret exhibited a dynamic switching behaviour with photo-writing and electrical-erasing processes. We found that the BCPs with a high PS content provided improved device performance, which could be explained by two aspects: (1) the enhanced β-conformation of the PFO strengthened the electron-trapping capability, (2) the well-dispersed and microphase-separated morphology stabilized the trapped electrons on the interface of PFO and PS domains. Consequently, PFO5k-b-PS22koutperformed in terms of the photo-responding current along with having a high current on/off ratio of 104and exhibited a retention time of more than 10?000 s. Our experimental results revealed the effectiveness of using the design based on a BCP for application in photonic FET memory devices. ? The Royal Society of Chemistry 2020.Block copolymers; Electrets; Field effect transistors; Image processing; Morphology; Conjugated block copolymers; Device application; Device performance; Electron trapping; Microphase-separated morphology; Photonic transistors; Poly(9 ,9-dioctylfluorene); Structure performance; Photonic devices[SDGs]SDG7journal article10.1039/d0tc05326k2-s2.0-85100472893