Biphasic Dielectrophoresis of Isotropic Pocket Carriers Containing Quantum Dots (QDs) in Nematic Medium and Fabrication of QD Cluster Array with Matrix Emission of Point Light Sources

Unusual physical properties of an anisotropic liquid crystal (LC) medium, such as topological defects, elastic interaction with particles, and nonlinear electrophoresis, are ingeniously utilized to handle nanoparticles. Here, a new approach to manipulate quantum dots (QDs) using volume-tunable and electrically movable isotropic pocket carriers in a nematic medium is demonstrated. This method is based on multiple mechanisms: spontaneous formation of QD flocs in LCs, sharp solubility contrast of QDs in nematic and isotropic phases, and biphasic dielectrophoresis in isotropic–nematic mixture. By thermally and electrically controlling the isotropic pockets containing QDs, an array of hierarchical QD clusters with the arbitrarily controllable size and location is fabricated. The phase boundary pressure squeezes the QD flocs to adhere to each other and on the substrate. The QD cluster array can be transferred to a flexible substrate, and can serve as a point light source array for display and image acquisition applications.