Photo-induced flexible semiconductor CdSe/CdS quantum rods alignment

The anisotropic absorption and emission from semiconductor CdSe/CdS quantum rods (QRs) provide extra benefits among other photoluminescence nanocrystals. Using photo-induced alignment technique, the QRs can be oriented in liquid crystal polymer matrix at a large scale. In this article, a 2D Dammann grating pattern, within "SKL" characters domains aligned QRs in composite film, was fabricated by multi-step photo exposure using several photo masks, and a continuous geometric lens profile pattern aligned QRs was realized by the single step polarization converting holographic irradiation method. Both polarized optical microscope and fluorescence microscope are employed to determine the liquid crystal director profiles and QRs anisotropic excitation properties. We have been able to orient the QRs in fine binary and continuous patterns that confirms the strong quantum rod aligning ability of the proposed method. Thus, the proposed approach paves a way for photo-induced flexible QRs alignments to provide a highly specific and difficult-to-replicate security application at a large scale.