Ho, Cheng HanCheng HanHoLin, Yi SaYi SaLinHung, Chih ChienChih ChienHungChiu, Yu ChengYu ChengChiuKuo, Chi ChingChi ChingKuoLin, Yan ChengYan ChengLinWEN-CHANG CHEN2023-02-082023-02-082022-01-012637-6113https://scholars.lib.ntu.edu.tw/handle/123456789/627775Organic phototransistors have been vigorously investigated for their superior charge-transport performance, photosensitivity, and compatibility with integrated circuits. Accordingly, liquid crystal molecules have been proven to be a high-performance organic electret, and discotic liquid crystal with a face-on orientation is able to show ultrafast photoresponse. Thus far, there is still no application of discotic liquid crystal as a charge-trapping electret in phototransistors. In this study, a series of discotic liquid crystalline molecules consisting of alkyl-triphenylene (Cx-TP, where x = 1, 6, 8, and 10) were designed and applied as an electret in the ultraviolet light-sensitive photomemory. The discotic liquid crystal with optimized side-chain length produced a homeotropically aligned nanoarray structure and endowed the best performance and photoresponse in phototransistor memory. Therefore, C6-TP- and C8-TP-based devices produced high memory ratios of approximately 103 and 104, respectively, which outperformed their analogues of C1-TP and C10-TP with a memory ratio of approximately 102. This achievement indicates the columnar hexagonal structure induced by the homeotropic alignment during liquid crystalline transition produces a huge impact on the photoresponse and device performance. The result of this study underlines the potential of discotic liquid crystals as a photoactive electret in phototransistor applications.field-effect transistor | hexagonal columns | homeotropic alignment | photomemory | triphenylene[SDGs]SDG7journal article10.1021/acsaelm.2c015652-s2.0-85146842776https://api.elsevier.com/content/abstract/scopus_id/85146842776